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)
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)
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)
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