Description Of Commercially Available Species
- 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.
- 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.
- 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)
- 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.
- binata var. multifida Similar to D. binata var. dichotoma except the leaf blade is divided into 6 or more linear sections.(Photo 4-11)
- 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.
- 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.
- 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.
- 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)
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
Summer 70-100°F (21-38°C). Winter 38-45°F(3-7°C). Some will survive subfreezing temperatures.
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.
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.
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.
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.
The best medium for propagation of most species is live sphagnum followed by nonliving sphagnum moss.
- 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.
- 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 _
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