Drosera anglica H u d s

BOTANICAL NAME: Drosera anglica Huds. Unacceptable synonym: Drosera longifolia. RANGE: In the west, from the Aleutians south to Alberta, western Montana, and into northern California; in the east, from Labrador west into the Great Lakes area.

FLOWERING SEASON: June to August.

TRAP SEASON: Spring and summer. Forms hiber-

nacula.

DESCRIPTION. - The leaves are semidecumbent (partially reclining) with rather long petioles reaching 3 to 4 cm. The blades are pale green with bright red,

stalked glands, and are longer than wide, measuring to 2.5 by 1.0 cm. The flowers are most often white.

GENERAL. — This very attractive sundew is especially interesting to botanists because there is pretty good evidence that it has evolved from two other contemporary species, D. linearis and D. rotundifolia. The simple hybrid between these two, frequently found where they are sympatric, is sterile. However, if the number of chromosomes of the cells of the hybrid embryo is doubled through an accident of cell division (amphi-ploidy), then the flowers of the plant growing from this embryo will be fertile, and the plant will reproduce sexually true to species. The sterile hybrid and the fertile hybrid (D. anglica species) look very much the same outwardly, although microscopic examination discloses larger cells in the amphiploid specimens. In view of the origin of the plant, some botanists would prefer to write it as a hybrid all the time (D. x anglica), rather than as a species, and they would simply note whether the particular plant is sterile or fertile. There remains one very perplexing problem: given the geologic sequence of events in North America, how does D. anglica happen to occur in the west and even in Europe, where no D. linearis has ever been recorded?

This bright sundew occurs in acid sphagnum bogs, or on acid mossy hummocks in marl bogs, frequently in the company of its probable ancestors.

Fig. 5-6. D. anglica. The leaf blade is somewhat oval, is pale green, and has red glands.

Drosera intermedia Hayne

BOTANICAL NAME: Drosera intermedia Hayne. RANGE: In suitable locations over most of the eastern third of North America.

BOTANICAL NAME: Drosera intermedia Hayne. RANGE: In suitable locations over most of the eastern third of North America.

Fig. 5-7. D. intermedia, plant in flower. While the leaves resemble those of D. anglica, the blades are somewhat narrower and smaller, and there is more red pigment in the leaf tissue. One can see the longer stem formation, even in this early summer plant.

FLOWERING SEASON: June to August.

TRAP SEASON: Spring and summer. Forms hiber-

nacula.

Fig. 5-7. D. intermedia, plant in flower. While the leaves resemble those of D. anglica, the blades are somewhat narrower and smaller, and there is more red pigment in the leaf tissue. One can see the longer stem formation, even in this early summer plant.

Fig. 5-8. D. intermedia leaf from shade-grown plant (so red pigment of sun-grown plants would not interfere with photographic contrast). Note the longer-stalked peripheral, or trapping, glands and the almost sessile central digestive glands. Several stalked glands are bent over the remnants of small prey.

Fig. 5-8. D. intermedia leaf from shade-grown plant (so red pigment of sun-grown plants would not interfere with photographic contrast). Note the longer-stalked peripheral, or trapping, glands and the almost sessile central digestive glands. Several stalked glands are bent over the remnants of small prey.

DESCRIPTION. — This species is unusual in that the plant stems are quite long. In fact, the plant can reach a height of up to 20 cm as the season progresses. The left has much the same form as in D. anglica, except that the trapping blade is shorter and narrower (0.5 by 1.0 cm) and has a diffuse, dark red color when growing in the open. The flowers are usually white.

GENERAL. — This species has the largest range of any species of Drosera in the eastern part of North America. In the southeastern coastal plain, the species reaches its greatest size, and often the whole plant is deep red. It is regularly seen in more wet areas, particularly on the margins of streams, ponds, and drainage ditches, where it will grow into the water and sometimes over the surface in dense mats. The phenomenon of vegetative apomixis can be observed frequently in D. intermedia. (See Chapter 2, p. 21, for a discussion of vegetative apomixis.)

0 0

Post a comment