Temperate Drosera

NATURAL HABITAT

Discussed in this section are the Drosera species that grow in the temperate climatic regions of the world. A few species listed in this section are also listed with the tropical Drosera species because they grow in both climatic regions.

DESCRIPTION OF PLANT

The growth habit of plants in this group varies from prostrate rosettes to erect. (Photo 4-7) Leaf shape ranges from almost round to thread-like. Flowers are various shades of red and white. (Photo 4-8) A few species produce tubers. All the species listed in this section survive temperatures that dip to about 40°F (4°C) during the winter or the plants' dormant period. Some species produce winter buds, called hibernaculum; others simply cease to grow, retaining their leaves during dormancy. The winter bud is a small tight cluster of undeveloped leaves surrounding the growing point. (Photo 4-9) It is formed at the center of the crown or rosette of leaves and usually after formation, the old leaves die back.

SPECIES AND HYBRIDS OF THE TEMPERATE TYPE OF THE GENUS DROSERA D. aliciae * D. anglica A—* D. arcturi A D. auriculata F—C—* D. binata var. binata A—B D. binata var. dichotoma A—B D. binata var. multifida A—B D. brevifolia E—* D. burkeana * D. burmannii D—* D. X californica A D. capensis * D. capillaris * D. cistiflora F—C—* D. cuneifolia F-* D. filiformis var. filiformis A—* D. filiformis var. tracyi A—* D. glabripes D. glanduligera D—* D. spp. golden sundew D. hamiltonii D. hilaris D. X hybrida A D. intermedia A-* D. linearis A—* D. montana * D. X Nagamoto A D. natalensis * D. X obovata A D. peltata F—C—* D. ramellosa F—C—* D. regia —B D. rotundifolia A—*

D. spathulata * D. stenopetala * D. trinervia D. villosa D. whittakeri C KEY

A= Aboveground parts of the plant die back to a winter bud or a growing point. B= Aboveground parts remain evergreen at temperatures of about 45°F (7°C) or above and will die back at lower temperatures. C= Aboveground parts die back leaving a viable tuber or rhizome in the soil. D= An annual.

E= Can behave as either an annual or perennial. F= Dormant during the summer. * = Will self-pollinate.

DESCRIPTION OF COMMERCIALLY AVAILABLE SPECIES

D. aliciae The wedge-shaped leaves form a compact rosette. Flowers are light purple to pink. Evergreen growth habit. Leaves are 2 in. (5 cm) long. Some consider it to be a member of the D. spathulata complex.

D. auriculata Form is similar to D. peltata. Both a basal rosette and elongated stem are produced. They can be distinguished by sepal characteristics, D. auriculata has glabrous sepals with black dots while D. peltata has pubescent sepals.

D. binata var. binata Erect linear leaves fork to form a "Y". The leaves can reach lengths of 20 in. (51 cm). Flowers are white. Goes dormant in winter when exposed to low temperatures. (Photo 4-10)

D. binata var. dichotoma Similar to D. binata var. binata except the leaves are divided into 4 linear segments. The dichotomy is sometimes irregular with more or fewer divisions occurring in some leaf blades.

D. binata var. multifida Similar to D. binata var. dichotoma except the leaf blade is divided into 6 or more linear sections.(Photo 4-11)

D. brevifolia The wedge-shaped leaf blades gradually taper to a short petiole. The leaf blade length is 0.2-0.7 in. (0.5-1.8 cm) and is usually longer than the petiole. The small plant forms a basal rosette. One to 8 white to rose-pink flowers are borne on a glandular-pubescent scape.

D. burmannii The blunt-ended spathulate leaves tend to have an overall maroon coloration and very long tentacles. The growth form is a basal rosette. Flowers are usually white but may be red.

D. burkeana A rosette with prostrate leaves, petiole up to 0.8 in. (2 cm) long with a roughly triangular-shaped blade that is up to 0.4 in. (1 cm) long and 0.3 in. (0.8 cm) wide. From 2-12 pink or white flowers are borne on each scape.

D. capensis Leaves erect with the blade curving gracefully downward. The leaf blade is linear and about as long as the petiole with the entire leaf being 2.8-5 in. (7-13 cm) long. Numerous pink flowers are borne on each scape. (Photo 4-12)

D. capillaris Leaf blades are longer than broad, and are egg-shaped. Leaf length is 0.4—1.2 in. (1-3 cm). Leaves form a prostrate rosette. This plant is often mistaken for D. rotundifolia. The species can be distinguished from each other by the leaf blades. D. rotundifolia leaf blades are broader than long while D. capillaris blades are longer than broad. One to 12 rose-pink to white flowers are borne per scape.

D. filiformis var. filiformis Erect thread-like leaves have no distinction between blade and petiole. Circinate vernation is evident in uncoiling of the leaves whose length is 0.4-12 in. (l-30.cm). One to 25 purple flowers are borne on each scape. Winter buds are formed during dormancy.

D. filiformis var. tracyi Differs from D. filiformis var. filiformis in that it is more robust. Leaves are longer and floral parts are larger. Tentacles are green rather than red.

D. intermedia Elongated, somewhat oblong-shaped blades are borne on the ends of semi-erect petioles. The leaf blade is about 4 times longer than wide and tapers to a long, slender petiole forming a leaf that is about 2 in. (5 cm) long. Leaves usually form a rosette, but when the environment is extremely wet, the leaves develop on an elongated stem. There may be 1-20 white flowers on a single scape. Winter buds are formed during dormancy.

D. hamiltonii The basal rosette consists of leaves 1.5 in. (4 cm) long. The leaves have narrow blades tapering into the petiole. The scape bears from 5-12 bright pink flowers. Growth ceases during dormancy.

D. peltata The leaves forming the basal rosette are round. The long petioled leaves on the erect stem, which may be 10 in. (25 cm) high, are peltate and shield-shaped. Several white flowers are borne on the scape. Plant is dormant during the summer with the aboveground part of the plant dying, leaving a viable underground tuber.

D. rotundifolia Leaves consist of a round to broader than long blade attached to a long narrow petiole. Leaves are about 3.5 in. (9 cm) long. Growth form is prostrate. One to 25 white to pink flowers are borne on a single scape. A winter bud is formed during dormancy.

CULTURAL INFORMATION Planting Media

Sphagnum peat moss, sphagnum moss (living or dried), sand, mixtures of sand with sphagnum peat moss, mixtures of sphagnum peat moss with vermiculite and/or perlite. D. linearis grows in both slightly alkaline and acid soils in nature. An alkaline medium suitable for this species is made from 1 part sand and 1 part vermiculite with or without 1 tablespoon of ground limestone or dolomite stone per quart of medium mixture.

Temperatures

Summer 70-100°F (21-38°C). Winter 38-45°F(3-7°C). Some will survive subfreezing temperatures.

Dormancy

Plants listed in chart 1 with an A after their name (not A-B) must have a dormant period at temperatures of 38-45°F (3-7°C) for 4-5 months. Most of these species will withstand subfreezing temperatures, although temperatures this low are not necessary for dormancy. D. linearis is particularly sensitive to changes in temperatures and photoperiod during its dormancy period. Toward late August or early September (in the Northern Hemisphere) light intensity and temperatures should be reduced to prepare D. linearis for dormancy which is manifested by the formation of a winter bud. Once initiated it is very important with this species to keep dormancy conditions constant for at least 5 months.

Photoperiod should be from 8-10 hours with a temperature close to or at freezing so that dormancy will not be broken prematurely, resulting in subsequent weak vegetative growth. The other species in the temperate group will survive the winter temperatures listed under the section on temperature but they will also thrive the year around at the temperatures given for the summer season. One advantage of lowering the temperature for these species during the winter is that the temperature change promotes uniform flowering in the spring.

Water & Humidity

All species require high humidity and a wet medium during the growing season. The medium should be drier during dormancy.

Light

Temperate Drosera can be exposed to direct or filtered sunlight. Under artificial light start with 1,000 foot candles for a 14-16 hour photoperiod during the growing season and 800 foot candles for an 8-10 hour photoperiod during the dormant season. Species that form winter buds do not need any light during dormancy.

Pests

Aphids, mites, mealy bugs, and Botrytis. See Chapter 8 for control measures. Feeding

See Chapter 7 for feeding directions. Miscellaneous

D. linearis thrives best if summer temperatures do not exceed 80°F (27°C) with winter temperatures close to or about at freezing temperatures. D. linearis does not tolerate competition from other plants. D. peltata, D. auriculata, D. ramellosa, and D. cistiflora grow during the cool, moist, fall and winter and are dormant the rest of the year. The easier species to grow in this group include D. aliciae, D. binata var. binata, D. binata var. dichotoma, D. binata var. multifilda, D. burmannii, D. capensis, D. capillaris, D. hamiltonii, D. montana, D. X Nagamoto, and D. spathulata.

PROPAGATION

Sexual Reproduction

Some temperate Drosera species will self-pollinate and produce viable seed while others will not. Some species such as the D. binata complex must be pollinated with pollen of plants from another clone. Some species have never flowered under culture while others have flowered profusely but never set seed. As far as is known none of the Drosera hybrids will produce viable seed as the Sarracenia hybrids do. Those plants that are self-fertile to our knowledge are identified by an asterisk following their name on pages 92-93. The seeds from plants that form winter buds must be stratified. Experience has shown that stratification is not detrimental to seed from species that do not form winter buds, such as D. spathulata and, in fact, results in a more uniform germination rate. Sow seed on the soil surface followed by a sprinkling of fungicide. Keep the humidity high, place seed in bright light and keep them within a temperate range of 70-85°F (21-29°C). Germination is quite variable for different species. Through experience we have learned that some seeds which are supposed to germinate in a few weeks will, at times, take a year or more. We keep all sown seed for at least 2 years before giving up and discarding them.

Asexual Reproduction

The best medium for propagation of most species is live sphagnum followed by nonliving sphagnum moss.

1. Leaf cuttings: To our knowledge all of the temperate species except D. spathulata, D. aliciae, D. regia, D. arcturi, and D. whittakeri can be propagated by leaf cuttings. Remove the whole leaf, being careful to include the leaf petiole. Place the cutting on damp soil, keep humidity high, and in strong light. Maintain leaves at 70-80°F (21-27°C). An easy way to maintain the leaf cuttings is to put the medium, preferably sphagnum moss, and leaves in a plastic bag. Insert a rod into the soil in the bag then blow up the bag and fasten the top of the bag to the top of the rod. The plastic bag acts as a mini-greenhouse requiring virtually no attention. The rod will support the bag and prevent the sides from falling on the leaf cuttings. We have found that leaves of the D. binata complex, D. capensis, D. intermedia, D. capillaris, D. rotundifolia, and D. X Nagamoto will root when floated in water. This is not a complete list as we have not tried leaves from all temperate species.

2. Root cuttings: Gently probe the medium around the plant until a root is located. Roots can be removed from a plant without uprooting the entire plant. Then remove the medium around it. Cut off about half the length of the root. About half of each root can be removed from a plant without any detrimental effect. If the plant has been growing in a relatively small pot for a year or so, the roots will often be found growing around the edge and bottom. In this situation allow the medium to dry out a little and then invert the pot holding the plant and tap the edge of the pot sharply. The plant with a ball of medium should fall out of the pot. Locate the thickest roots and cut them off. Cut the roots into 1 in. (2.5 cm) pieces, lay them on damp sphagnum moss, keep the humidity high, maintain in strong light at a temperature range of 70-85°F (21-29°C).

Species which are known to be amenable to this technique are D. binata var. binata, D. binata var. dichotoma, D. capensis, D. hamiltonii, D. spathulata, and D. regia.

Tropical Drosera _

NATURAL HABITAT

This group of Drosera grow in tropical areas of the world. Their habitat is quite diverse, some growing in a wet, humid environment the year around while some live in a Mediterranean-type climate which has a wet season and a dry season.

DESCRIPTION OF PLANT

The growth habit of plants in this group varies from rosettes which tend to be prostrate to erect plants. Leaf shape varies from round to almost linear. Flowers are shades of red and white. A few of the species produce tubers.

SPECIES OF THE TROPICAL TYPE OF THE GENUS DROSERA

We have listed only those species for which cultural information is presently available. Thus, our list does not pretend to be complete. Some species are also listed with the temperate Drosera because they will also grow under temperate environmental conditions, except they will not survive a frost, and grow much better at higher temperatures. D. adelae D. affinis D. banskii D. burkeana

D. burmannii—an annual D. indica—an annual D. madagascariensis D. peltata D. petiolaris D. pilosa D. prolifera D. schizandra D. spathulata

DESCRIPTION OF COMMERCIALLY AVAILABLE SPECIES

D. adelae Erect with narrow lanceolate leaves, 4-10 in. (10-25 cm) long, crowded on a short stem. Scapes 1-3 with numerous red flowers on each. (Photo 4-13)

D. burkeana A rosette with oval leaves. The petiole is narrow, up to 0.8 in. (2 cm) long, broadening abruptly into the blade which is about 0.4 in. (1 cm) long. Two to 12 white or pink flowers are borne on each scape.

D. burmannii A basal rosette with reddish leaves having unusually long tentacles. The circular blade is about 0.47 in. (12 mm) long and 0.43 in. wide narrowing to a short flat petiole. There are 1-5 scapes per plant with 3-14 white flowers on each.

D. peltata Described in Temperate Sundew section.

D. prolifera A basal rosette that is semi-erect. Petiole is narrow, 2 in. (5 cm) long attached to a kidney-shaped blade 0.6 in. (1.5 cm) long and 0.8 in. (2 cm) wide. The scapes (1-3) bear 2-6 pink to red flowers and tend to trail on the soil surface. There is a vegetive bud at the end of the scape that will develop into a plant.

D. schizandra Large leaves form a rosette from which a short scape bearing 2-6 white flowers emerges. The leaf petiole is very short while the blade can be up to 5 in. (13 cm) long and 2.5 in. (6 cm) wide with or without a notch on the end or apex of the blade.

D. spathulata Leaves whose outline varies from spoon-shape to wedge-shape form a basal rosette. This species is widespread geographically and the shape of the leaf varies in different areas resulting in plants that appear to be distinct species. The group is referred to as the Spathulata Complex. Petioles are up to 1 in. (2.5 cm) long, gradually widening to the blade that can be up to 0.5 in. (1.3 cm) long. One to 15 white or pink flowers are borne on each scape which can number from 1 to 3.

CULTURAL INFORMATION Planting Media

Sphagnum peat moss, sphagnum moss (living or dead), one part sphagnum peat moss to one part perlite, or one part sand and various mixtures of sphagnum moss and sphagnum peat moss.

Temperatures

Summer: 70-95°F (21-35°C). Winter: 60-70°F (16-21°C). Tropical Drosera can be grown year around at the summer temperatures given above, but for most, a lower winter temperature insures more uniform flowering in the spring.

Dormancy

D. peltata dies back during the summer leaving a viable tuber in the soil and resumes active growth during the winter. The other tropical Drosera, except the annuals, usually grow very little, if any, during the winter season.

D. burmannii and D. indica are annuals. To maintain a supply of plants, their seed must be collected and sown each year. Allowing the seed to fall to the surface of the soil in the pot and regrow in the same soil is satisfactory for a few years, but the soil should be changed every 3 years or sooner if growth is not as vigorous as before and/or if plant pests appear.

Allowing the seed to drop and germinate at the base of the plant will result in a very thick crop of young plants which must be thinned to avoid an environment conducive to fungal infections. It is usually efficacious to collect the seed and sow the amount required for your needs and save the rest.

D. petiolaris should have reduced water during the summer. (Photo 4-14) The soil should be much drier during the summer than winter, but not thoroughly dry. During the winter, its normal growth period, the temperature should be in the summer range and the soil should be wet. The other tropical Drosera species usually cease to form new leaves during the winter.

Water & Humidity

All species require high humidity and wet medium during the growing season. The medium should be drier when they are not actively growing.

Light

All of the tropical Drosera grow in bright light in their native habitat save for D. adelae, D. prolifera and D. schizandra which grow in shaded areas. We have grown D. prolifera and D. adelae in very bright light without any apparent harm, but the leaves are smaller than when grown in subdued light. We have found that D. schizandra grows best in weaker light. When under artificial light use 1000 foot candles with all species except for D. schizandra which should be at about 750 foot candles. Photoperiod: Growing season about 14 hours, dormant season about 11 hours.

Pests

The only pests we have had are aphids and fungus. See Chapter 8 for treatment. Feeding

See Chapter 7 for feeding instructions. Miscellaneous

D. schizandra grows best in living sphagnum moss and with a relatively uniform temperature. It apparently requires extremely high humidity, as it does not grow well in the greenhouse in which we grow our Nepenthes. We provide a higher humidity for D. schizandra plants by planting them in living sphagnum moss and placing them in sealed plastic bags which are then kept in the Nepenthes greenhouse. The result is much better growth. The easier species to grow in this group include D. adelae, D. burmannii, D. prolifera, and D. spathulata.

PROPAGATION

Sexual Reproduction

To our knowledge D. burmannii, D. indica, D. burkeana, D. affinis, D. spathulata, D. madagascariensis, D. pilosa, D. peltata, and D. banksii will flower, self-pollinate, and produce viable seed under cultivation. Although our D. adelae and D. prolifera flower profusely, they have never set seed. Cross-pollination efforts have not been successful. D. petiolaris and D. schizandra flower occasionally but neither one has produced seed. Sow seed on the surface of the planting medium, maintain a high humidity and bright light with a temperature range of 70-95°F (21-35°C).

Asexual Reproduction

1. Leaf cuttings: All the species except D. burmannii, D. indica, and D. spathulata will produce new plants from leaf cuttings. Remove the entire leaf including the petiole, place it on damp planting medium, preferably living sphagnum moss, keep the humidity high, the light bright and at a temperature from 70-85°F (21-29°C). Once new plants are fully rooted they can be transplanted.

2. Stolons: D. prolifera produces scapes that sometimes bear flowers, while at other times produce plants. To further complicate matters, the same scapes sometimes produce both flowers and plantlets. (Fig. 4-6) When the plantlets produce a root system they can be severed from the mother plant and transplanted. (Photo 4-15) We have found it is best to sever the plantlet from the mother plant about 1 month in advance of transplanting it. The latter technique helps insure against losing the plantlet when transplanting.

3. Root cuttings: D. adelae, D. prolifera, D. schizandra, and D. spathulata will reproduce from root cuttings. Select fleshy (thicker) roots, cut them into 1-2 in. (2.5-5 cm) lengths and follow the procedure given for leaf cuttings. This procedure may work with other species in this group also. (Fig. 4-7)

4. Decapitation: The aerial part of the plant is cut away from the root system just below the crown. The removed part is treated as a cutting would be and will develop roots in 1-2 months. The roots left in the medium will produce new plants. All species that can be propagated by root cuttings are amenable to this procedure.

5. Stem cuttings: D. adelae, D. affinis, and D. pilosa can be propagated by stem cuttings. Remove 2-3 in. (5-8 cm) from the top of the plant and place the removed section in sphagnum moss. Keep the cutting under the same conditions as prescribed for leaf cuttings. The remaining portion of the mother plant will continue to grow.

Fig. 4-6 Drosera prolifera plant. Leaves form a rosette. Flower scapes sometimes bear flowers or plantlets or both.

Fig. 4-7 Plantlets of Drosera adale produced by means of root cutting.

Drosophyllum _

HISTORY

Drosophyllum's ability to capture insects was well known for hundreds of years before any thought was given to its possible carnivorous nature. Darwin investigated Drosophyllum for carnivory, but it was A. Quintanilha of Portugal who did the critical study of Drosophyllum, verifying that it secreted a digestive enzyme that effected digestion without bacterial assistance. The first part of the name Drosophyllum is derived from the Greek drosos, meaning dew, and phyllum is from the Greek phylon for race or tribe.

NATURAL HABITAT

Drosophyllum lusitanicum is the only species in the monotypic genus, Drosophyllum of the Droseraceae. It grows in a relatively dry environment in rocky, sandy soil. All the wild plants are found in Spain, Portugal and Morocco. In its native habitat it is subjected yearly to a wet and a dry season. During the summer, which is the dry season, the plants obtain moisture from the dew and/or fog which is prevalent where they grow.

DESCRIPTION OF PLANT

D. lusitanicum is an erect, woody shrub that can grow to be 4.5 ft. (1.4 m) high with a fibrous root system. The long, narrow, tapering, linear leaves are light green and reach lengths of 10 in. (25 cm). Each leaf has a groove along its length on the upper surface. The leaves do not abscise when they die, but rather droop down to the ground forming a "grass skirt" around the base of the stem. Each leaf is clothed with 2 types of glands: the stalked tentacle glands which produce the mucilage for trapping prey and the sessile glands which secrete digestive enzymes upon stimulation and also absorb the products of digestion. Tentacles are most abundant on the under surface and along the edges of the leaves while sessile glands occur on all leaf surfaces. The tentacles are similar to those found on Byblis leaves, in that they do not move when capturing prey. Tentacles develop a red coloration when exposed to strong light. While the plant is a perennial in. nature, when grown under conditions of constant high soil moisture it grows as a biennial. (Fig. 4-8)

Flowers

The bright yellow flowers which can be 1.5 in. (4 cm) in diameter are borne in panicles. In its native habitat flowering occurs during April and May. Under greenhouse conditions the plants flower during the summer or fall. The flowers, having 5 sepals and 5 petals, open during the day and close at night. The plants are self-fertile and will produce viable seed without any outside pollinating agent. (Photo 4-16)

TRAPPING

Luring is accomplished by the red coloration of the tentacles and the honey-like odor of the mucilage. After landing on the leaf, prey is captured when, because of its struggle to free itself, it becomes mired in the mucilage of the tentacles. The tentacles are not active in prey capture. The sessile glands secrete digestive enzymes and then absorb the products of digestion. (Photo 4-17)

SPECIES OF THE GENUS DROSOPHYLLUM

D. lusitanicum

CULTURAL INFORMATION

Planting Media

Sphagnum moss (living and nonliving), sphagnum peat moss, 1 part sphagnum peat moss to 1 part perlite or 1 part sand, 1 part sphagnum peat moss to 3 parts sand or 3 parts perlite. Some growers add powdered limestone or dolomite at a rate of 1 teaspoon (5 ml) per quart (liter) of medium.

Temperatures

Plants will survive a light frost and temperatures up to 100°F (38°C). They grow best at lower temperatures of 40-75°F (4.5-24°C).

Dormancy

In their native habitat Drosophyllum plants usually cease to grow during the hot, dry summers. Consequently, when grown in culture the planting medium must be drier during the dormant period.

Water & Humidity

The key to growing this plant as a perennial is to use a well-drained medium which is kept slightly moist. If the medium is constantly wet, the plant will grow as a biennial. When growing plants from seed, medium is kept wet until the seeds germinate and thereafter on the dry side until the seedlings are 4-6 in. (10-15 cm) high.

Light

Drosophyllum plants grow best in strong light and will thrive in full sunlight. If they do not receive enough light they develop elongated internodes, weakening the stem and causing it to fall and grow along the surface of the medium. When this happens the

Fig. 4-8 Whole Drosophyllum plant.

suppressed buds in the leaf axils will start to grow, producing secondary stems along the primary stem resulting in an unusually shaped plant.

With strong light Drosophyllum plants will grow into compact shrub-like structures with very short internodes and red colored tentacles. (Photo 4-18)

If using artificial light provide the plants with at least 1500 foot candles. Photoperiod: summer about 14 hours, winter 10 hours.

Pests

The known pests are mealy bugs, aphids, and fungus. See Chapter 8 for treatment. Feeding

See Chapter 7 for feeding directions. Miscellaneous

Once Drosophyllum plants have reached heights of 4-6 in. (10-15 cm) they can be watered freely or kept in standing water and will grow well. Under these conditions they will grow as biennials and will produce viable seed the second year. The seed assures a steady supply of plants. A few precocious plants will flower the first year but usually do not produce viable seed. First-year flowers should be removed so that the plants can direct their energy to vegetative growth.

Plants can be grown as perennials by adhering to the following procedure. Use a planting medium of 1 part sphagnum peat moss to 3 parts sand or perlite. Keep the medium wet until the seed germinates. Following establishment maintain the plants in an almost dry medium. The plants will grow continuously for several years in this almost dry environment. We have one plant that has been growing for 8 years. The key for maintaining Drosophyllum plants as perennials is to use a well-drained medium and to keep it damp but not wet.

Plants grow much larger when a single plant is grown per pot. The plants produce a chemical that inhibits the growth of nearby plants of the same species.

PROPAGATION

Sexual Reproduction

Flowers self-pollinate to produce viable seed. When the seeds are mature they will be visible in the translucent, cone-shaped seed pod. The seed is enclosed in a hard coat which inhibits germination. If the seeds are not treated, germination can take up to 4 years. To encourage germination scratch the seed coat. When the seed coat is scratched, germination usually takes place within a month.

We have discovered that cutting a very thin slice from the widest end of the seed greatly speeds germination. When done correctly a white color should be visible inside the seed coat. (Fig. 4-9)

There are reports that soaking the seed for about 10 minutes in a strong solution of detergent will hasten germination. Seeds will germinate at temperatures as low as 40°F (4°C), but they take longer at this low temperature, so we recommend maintaining the temperature at 70°F (21 °C). Since Drosophyllum plants grow most actively during cool, wet winters, the seed should be planted in late summer or early fall so that the plants will be well developed before the summer.

Drosophyllum plants inhibit each other's growth. Therefore, plant only one plant per pot, if large plants are desired. To insure that you will end up with one plant per pot, plant 2-3 seeds in each. Plant seeds about 0.25 in. (0.6 cm) below the medium surface. If the intention is to transplant the extra seedlings, the seed should be planted as far apart as possible. After germination the largest and strongest seedling is left in the pot. These plants are almost impossible to transplant successfully except in the seedling stage. It is important when transplanting the seedlings to move them with as large a ball of medium as possible. Medium should be kept quite damp or wet until the seeds germinate and thereafter kept on the dry side to prevent both damp-off, (that is, a fungus infection,) and a biennial growth pattern. Spraying the medium and seeds with a fungicide will help control damp-off. After the plants reach a height of 4-6 in. (10-15 cm) the danger of damping off is minimal.

Asexual Reproduction

None reported to date.

Fig. 4-9 How a seed is cut to hasten germination.

Byblis_

HISTORY

The genus was formerly classified as a member of the families Lentibulariaceae and Droseraceae but now is classified in Byblidaceae. Byblis gigantea was first discovered by James Drummond. The carnivorous nature of Byblis was suggested by Ms. A. Nikon Bruce during the early 1900s. Byblis gigantea and B. liniflora are the sole species in this genus and are indigenous to Australia and New Guinea. The name Byblis is derived from the Greek word "byblis" which refers to a nymph who loved her brother.

NATURAL HABITAT

Byblis gigantea is a perennial that grows in southwestern Australia in sandy soils in areas marked by hot, dry summers and cool, wet winters. In areas where the soil dries out, the plants die back to their rootstock during the dry season with new growth produced after the arrival of rain. In places where the soil is moist all year, the plant does not die back but rather is evergreen.

Byblis liniflora grows in northern Australia and New Guinea usually in sandy soils. Much of the area in which it grows is dominated by monsoonal weather, with a wet season during the hot summer (December-April) and a dry season during the winter in which temperatures range from 60-104°F (16-40°C). In areas where the soil is wet part of the year and then dries out, B. liniflora grows as an annual, but in permanently moist situations it is a perennial.

DESCRIPTION OF PLANTS

Byblis gigantea is an erect, shrub-like plant reaching heights of 28 in. (71 cm) having yellow to pale yellow-green leaves and grows from a rhizome. The plant usually has one main, aboveground stem, but older plants may develop more than one main stem and occasionally side branches. The long linear leaves taper to a point at the apex and can reach lengths of 12 in. (30 cm). In cross-section the base of the leaf is triangular with rounded edges but becomes almost circular in cross-section at the tip. Two kinds of glands clothe all the plant's aboveground surfaces. Tentacles are the stalked glands which produce the shiny, sticky mucilage that traps the prey. The sessile glands which produce enzymes to digest the prey are stalkless. (Photo 4-19)

Byblis liniflora is very similar to B. gigantea in structure except it is more refined and delicate. Its growth pattern is vertical until it reaches 6-12 in. (15-30 cm) at which height it tends to topple over and grow along the surface of the soil or on other plants. (Fig. 4-10) The plant may reach lengths of 35 in. (89 cm) in this growth habit. The individual leaves may attain lengths of 4 in. (10 cm). The tentacles and sessile glands, again, are the same as in B. gigantea but smaller and shorter.

Flowers

Flowers can reach diameters of 2 in. (5 cm) in Byblis gigantea and have petal color described as purplish red, lilac, magenta or reddish purple. The flowers are borne singly on scapes that arise from the leaf axils. The flowers open about midday and close in late afternoon; this process is repeated for several days. Flowers have 5 petals, 5 sepals and 5 stamens of unequal length that curve toward the pistil. (Photo 4-20) Flowering occurs in September, through December.

Floral structure is basically the same in B. liniflora as in B. gigantea, but the flowers are smaller and petal color is pale blue and occasionally white. (Fig. 4-11) Plants which grow as perennials tend to bloom irregularly, whereas those that grow in habitats where soil is moist part of the year and dries out the other part, bloom mainly in the wet season, which in their native Australia is from December to April.

TRAPPING

Prey is lured by the glistening droplets of mucilage on the tip of the tentacles. Insects are captured by becoming mired in the thick sticky mucilage on the leaf surface, where digestion and absorption also take place. The tentacles of Byblis do not move. As is the case in some other carnivorous plants, some insect species are, or at least appear to be, immune to these plants' digestive and trapping mechanisms and share in the plants' booty. One of these is the wingless caspid which is able to walk over the mucilage with impunity. This capability is observed but not understood.

SPECIES OF THE GENUS BYBLIS

B. gigantea

B. liniflora

CULTURAL REQUIREMENTS Planting Media

Sphagnum peat moss, sphagnum moss (living or dead), 1 part sphagnum peat moss to 1 part perlite or sand (coarse), or 1 part sphagnum peat moss to 2 parts perlite or sand (coarse). The latter mixture is the preferred medium. B. liniflora will grow as a perennial if the planting medium is maintained in a moist condition but not when wet or waterlogged.

Temperatures

B. liniflora: 65-90°F (18-32°C). B. gigantea: 40-80°F (4-27°C). Grows best at a temperature of at least 70°F (21°C), but less than 80°F (27°C).

Dormancy

B. liniflora is an annual in its native habitat where soils dry out part of the year. In situations of permanently wet soils it is a perennial. B. liniflora will grow as a perennial under culture if grown in a sandy, well-drained planting medium which is kept moist but not soggy.

B. gigantea dies back to its rootstock or base during the dry, hot Australian summer and grows during the cool, wet winter in areas where the soil dries out. In regions where the soil is moist, the plant is evergreen and does not die back to the rootstock.

Under cultivation it will not go dormant if kept moist, but the rate of new growth decreases during the winter. We maintain B. gigantea at 40°F (4°C) during the winter. With the arrival of spring and warmer temperatures, the rate of new growth increases, accompanied by profuse flowering until late fall or early winter when growth slows or ceases. The plants remain evergreen during the winter. The second, and subsequent springs, the plants will do one of two things. On the one hand, the new growth starts at the base at which time the top of the plant dies back to the base. Alternatively, the plant puts forth new growth from the top of last year's stem. When top growth occurs the plant must be physically supported for the season with a stake.

Water & Humidity

High humidity and moist soils are needed for B. liniflora at all times and for B. gigantea during the growing season. Keep the planting medium much drier during the dormant season.

Light

Although B. liniflora grows near the equator, it is shaded by other plants. Indirect or shaded sunlight is suitable and if using artificial lighting, start with 1200 foot candles for a 14 hour photoperiod for B. liniflora.

Some direct sunlight is good for B. gigantea during the season of active growth. If using artificial light, start with 1200 foot candles for a photoperiod of 14-16 hours during the active growing season and 800 foot candles with a photoperiod of about 9 hours during the resting period.

Pests

Aphids and fungus. See Chapter 8 for control. Feeding

See Chapter 7 for feeding directions. Miscellaneous

As B. gigantea plants grow older they tend to become straggly and rather unsightly. To remedy, cut off the top of the stem leaving 1-2 in. (2.5-5 cm) above the base, just before the season of active growth begins. Use the top for a cutting as outlined in the section on asexual propagation. You will not only gain another plant, but the new growth that develops from the stump left in the pot will produce a compact plant.

B. liniflora usually is not able to support itself vertically, after reaching a height of about 5 in. (13 cm). When a plant attains this height it usually falls to the soil or on other plants. When this happens cut off the upper part of plant and root as a cutting. The original plant will then produce side shoots.

PROPAGATION

Sexual Reproduction

To insure fertilization of the flowers in both Byblis species the stamen, which is yellow, must be vibrated gently to induce it to give up its pollen. A toothpick or similar object is a useful device to assist in releasing the pollen. Follow this procedure every afternoon for a few days. The flower will close as darkness falls and reopen the next day. The yellow pollen is easily seen on the surface of the stigma and petals when it is released.

As the seeds develop, the ovary of the flower will swell. In 4-6 weeks the seed pod of B. liniflora will become translucent and dehisce (split) to release the seed. B. gigantea seed pods do not dehisce upon maturity, but rather dry up retaining their seed.

B. liniflora seed must be stored at least 2 months before planting. They can be dried for a few days at room temperature, placed in a vial or small plastic bag and stored under refrigeration for sowing at a later date.

B. gigantea seeds are much more difficult to germinate than seeds of B. liitiflora. In their native habitat, fire is apparently necessary to meet their dormancy requirement. Listed below are several methods which have been used successfully for treating seeds to promote germination.

1. Place the seed, which has been soaked for a day in water, on damp planting medium. Scorch both the seeds and the soil surface with a flame from a Bunsen burner or butane torch until steam (condensed water vapor) is visible.

2. Crumple a paper towel or a couple sheets of writing paper and place them on the surface of the damp planting medium on which seeds soaked in water for a day have been sprinkled. Ignite the paper. After burning the paper, carefully and thoroughly water the surface of the planting medium.

3. Pour boiling water over the seeds which have been sprinkled on the surface of the planting medium. Repeat at least 4 times in succession to be certain that the seed and soil have been heated sufficiently.

4. Soak a piece of filter paper or paper towel in a solution of 1 part of Gibberellin (75% Potassium Gibberellate salt) to 1000 parts of distilled water. Sprinkle the seed on the filter paper. The next day remove the seed from the paper and spread on the surface of the planting medium. Some growers prefer to leave the seed on the filter paper until it germinates, at which time the seedlings are transplanted to the planting medium. If the later procedure is followed, the filter paper must be kept damp using plain water.

After treating B. gigantea seed, follow the same procedure given for germinating B. liniflora seed. The seedlings of both species are very subject to damping off (fungus disease). To control the fungus, dust the seed with a fungicide. Keep humidity high, light bright and temperatures 70-90°F (21-32°C). Germination usually takes place within 2 months.

Byblis plants do not as a rule transplant easily, so if they must be transplanted do so while the plants are young seedlings. When transplanting, remove a ball of soil with the roots.

Asexual Reproduction

B. gigantea

1. Root cuttings: Carefully remove the soil on one side of the plant to locate a thick root. Remove about 2h of its length and recover the remaining root with medium. Cut the root section into 1 in. (2.5 cm) lengths. Place the pieces horizontally on the surface of sphagnum moss, preferably living. Keep the humidity high, light bright and the

Jr temperature 70-80°F (21-27°C). Several plantlets will usually develop along the length of each section within 6 weeks. After the plantlets have developed their own root system they can be severed from each other. This practice may be repeated yearly. In doing so, be sure to alternate sides of the plant for root removal.

2. Stem cuttings: If the plants are given a dormant period the top 6 in. (15 cm) of the stem is cut off before the stem dies back to the rootstock. If the plants are not given a dormant period, a cutting of similar length is taken just before active growth begins. Place the cutting in sphagnum moss following the same directions as given for B. liniflora stem cuttings. The cutting will root in about 3 months. The remainder of the original plant will produce a new stem.

B. liniflora

1. Stem cutting: B. liniflora will grow erect until it reaches 4-10 in. (10-25 cm), when it typically becomes top-heavy and topples to the ground, after which the terminal end of the plant will start to grow vertically again. A stem cutting about 2 in. (5 cm) long can be taken from the top of the plant before it tumbles over. The cutting, which should include the growing tip, is inserted in planting medium so that about xk of the stem is below soil level. Keep the humidity high, light strong and at temperatures 70-85°F (21-29°C).

When rooted, the plant will start growing again. This procedure provides both a new plant and a bushier mother plant due to increased side branching.

2. Leaf cuttings: Leaves removed from B. liniflora plants are placed on damp planting medium. Under conditions of high humidity and bright light they will produce plantlets.

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