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Acampe rigida
	Flowers
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Epidendroideae
Genus:	Acampe
Species:	A. rigida
Binomial name
	Acampe rigida; (Buch.- Ham. ex Sm.) P.F. Hunt (1970)
Synonyms
	List Aerides rigidum Buch.-Ham. ex Sm. (1818) (Basionym); Vanda multiflora Lindl. (1826); Vanda longifolia Lindl. 1833; Acampe longifolia (Lindl.) Lindl. (1853); Acampe multiflora (Lindl.) Lindl. (1853); Acampe intermedia Rchb.f. (1856); Acampe wightiana var. longipedunculata Trimen (1885); Saccolabium longifolium (Lindl.) Hook.f. (1890); Gastrochilus longifolius (Lindl.) Kuntze (1891); Acampe penangiana Ridl. (1896); Vanda viminea Guillaumin (1930); Acampe taiwaniana S.S. Ying (1974); ;

Acampe rigida is a species of orchid native to the forests of tropical southern Asia where it grows on trees and rocks at altitudes of up to 1,800 m (6,000 ft).

Description

Acampe rigida is a robust species with an unbranched stem up to 1 m (40 in) in length and 20 mm (0.8 in) in diameter. The leaves are distichous. The stem nodes are about 25 mm (1 in) apart and each bears a somewhat fleshy, upright leaf with sheathing base. The apices of the leaves are obtuse and unequally bilobed. The inflorescence is unbranched or sparsely branched, with many slightly fragrant, upturned, cup-shaped flowers less than 25 mm (1 in) in diameter. The petals are fleshy, and are yellow with purplish-brown stripes; they have a thick, white, three-lobed lower lip, and a short spur. They are followed by cylindrical or fusiform capsules.^[2]

Distribution and habitat

Acampe rigida is native to the Andaman Islands, Assam, Bangladesh, Bhutan, Cambodia, China, India, Laos, Malaysia, Myanmar, Nepal, the Philippines, Sri Lanka, Thailand and Vietnam.^[1]^[2] It occurs in forests, either growing epiphytically on the branches and trunks of trees, or growing on rocks, and often forming dense clumps. Its altitudinal range is from 300 to 1,800 m (1,000 to 6,000 ft).^[2]

Ecology

Acampe rigida is a deceptive orchid in that it produces a fragrance that may attract insects but does not then offer them any reward. It is self-compatible, but has not evolved any particular mechanism to enable self-pollination. In Guangxi province in southwestern China, it flowers in late August and September, at a time of year when rain falls almost daily and insect pollinators are scarce. In a research study, after many hours of observation, a single insect was observed to visit a flower, but pollination did not occur. Instead, the plant exhibited ombrophily; rain drops falling on the tips of the stamens knocked the caps off the anthers, and further drops caused the pollinia to be ejected upwards, after which strap-like stipes arrested their movement and caused them to land in the stigma cavity, resulting in self-pollination. A high rate of fruit set occurred, but without the action of the raindrops, self-pollination did not occur and fruit did not set.^[3]