The Cliff-Dwelling Deceiver
Dendrobium sinense, the Chinese Dendrobium, is a perennial orchid that grows as an epiphyte, clinging to tree trunks and limestone cliffs in the mountainous regions of southern China. First described by botanists Tang and F.T. Wang in 1974, this species thrives in open montane forests at elevations between 400 and 1,600 meters. The plant itself is small, with slender, cane-like stems called pseudobulbs that grow 5 to 21 centimeters long. These stems, which are covered in fine black hairs when young, carry several leathery, ovate-oblong leaves.
The flowers of Dendrobium sinense are its most deceptive feature. Blooming in the summer and fall, the single yellow flower measures 4 to 6 centimeters across and appears near the top of the stem. It is pollinated exclusively by a species of hornet, Vespa bicolor. The orchid produces no nectar to reward the hornet. Instead, it engages in chemical mimicry. The flower emits a unique volatile compound, (Z)-11-eicosen-1-ol, which is an component of the alarm pheromone of the Asian honey bee (Apis cerana), one of the hornet's primary prey animals. Lured by the scent of a distressed bee, the hornet aggressively pounces on the center of the flower, inadvertently picking up or depositing pollen in the process.