Bletilla, commonly known as the urn orchid, is a small temperate genus of terrestrial orchids in the family Orchidaceae (order Asparagales). The genus contains five accepted species native to East and Southeast Asia, with their range spanning China (across numerous provinces from Gansu and Shaanxi south to Yunnan and Guangdong), Japan, Korea, Taiwan, Vietnam, Thailand, and Myanmar.
Plants grow from pseudobulbs that resemble spreading corms and typically sit at or near ground level. Each pseudobulb produces several distinctly pleated, tapered leaves reaching approximately 40 cm in length. In spring and early summer, arching racemes of flowers emerge from the center of the current season's new growth before the leaves fully develop. Flower color ranges from white to purple across the genus, and all species share a characteristic of bearing four pollinia. The underground tubers are grayish-white to yellowish-white, horn- or claw-shaped with concentric rings, and notably hard in texture.
The genus name is a diminutive of Bletia, a morphologically similar but unrelated New World genus; the resemblance between the two led early botanists to coin the name. Two segregate genera, Jimensia Raf. and Polytoma Lour. ex Gomes, are generally included within Bletilla.
Bletilla striata is by far the most widely cultivated species and is sold in the nursery trade under names such as "Hardy Orchid" and "Chinese Ground Orchid." It holds the distinction of being one of the earliest orchids brought into cultivation in England, with records dating to around 1794. Established plants are surprisingly cold-tolerant, succeeding in gardens as far north as USDA Hardiness Zone 5 with adequate mulch.
Etymology
The genus name Bletilla is a Latin diminutive of Bletia, a New World orchid genus with which it shares a morphological resemblance, despite the two being geographically and phylogenetically distinct. The genus is abbreviated Ble in horticultural trade journals.
Distribution
Bletilla is native to East and Southeast Asia. Its five species are collectively distributed across China (in provinces including Gansu, Shaanxi, Sichuan, Yunnan, Guizhou, Guangxi, Guangdong, and others), Japan, Korea, Taiwan, the Ryukyu Islands (Nansei-shoto), Vietnam, Thailand, and Myanmar. Bletilla chartacea is restricted to Myanmar, while B. striata has the broadest range, extending from Japan and Korea through much of eastern and southern China.
Cultivation
Bletilla species are among the easiest orchids for beginners, requiring no extraordinary care. They prefer well-drained, evenly moist soil rich in organic matter and should not be allowed to dry out completely or remain waterlogged. During winter dormancy, watering should be reduced and potted plants moved to a frost-free location where temperatures drop below freezing. New growth in spring should be watered sparingly for the first four weeks, as new roots lag behind the emerging shoots.
Bletilla striata is hardy to USDA Zone 5 with heavy mulch and to Zone 6 with moderate mulch of straw or leaves; plants in the ground generally tolerate winter lows to about −4 °C (25 °F) without mulch. Late frosts can damage flowers and leaves and should be avoided with protective coverings. Established clumps become increasingly floriferous over time, with each shoot capable of producing up to fourteen rose-mauve flowers about 30 mm across, resembling a miniature Cattleya bloom. The white-flowered cultivar B. striata var. alba and the yellow-flowered species B. ochracea are also available to collectors.
