特徵描述
作者
SU, Horng-Jye
型態特徵
Terrestrial, epiphytic or saprophytic perennial herbs with rhizomes, corms, root-stem tuberoids or tuberous roots. Stems monopodial or sympodial, leafy or scapose, long or short, often thickened and forming pseudobulbs. Leaves radical or cauline, spiral or alternate and often distichous, convolute or conduplicate, variously shaped, sometimes all reduced to scales, often sheathed at base, sheath nearly always closed and encircling stem. Inflorescences terminal or lateral, spicate, racemose or paniculate, or with solitary flower; peduncles from various positious of stem, scapes from rhizome or base of pseudobulb. Flowers usually zygomorphic, often resupinate through twist of ovary for 180o, perianth epigynous, composed of 6 petaloid segments in 2 whorls, free or variously connate in each whorl; sepals (3 outer segments) imbricate or subvalvate; petals (3 inner segments) usually alternate to sepals, middle petal (lip or labellum) usually different in shape and often complicated in structure; lip variously shaped, sometimes 3-lobed, mostly placed in an abaxial position on account of resupination, base often produced into sac or spur; stamens and pistil fused together forming column, rarely separated; stamens 1 or 2, anthers 2-8-locular, sometimes with reduced partitions, opening by lengthwise slit, pollens rarely granular, generally agglutinated into masses or compact bodies (pollinia); pollinia mealy (powdery), sectile (consisting of small massulas) or waxy (bony), 2, 4, 6 or 8, naked (without definite accessory structure), or with accessory structures forming set of pollinarium, either with one end extended into softer sterile caudicle developed in anther and attached by caudicle to viscidium, or connected by sterile hyaline stipe developed outside anther, stipe derived from epidermis of rostellum (tegula stipe) or formed by apex of rostellum (hamulus stipe); ovary inferior, usually 1-locular with 3 parietal placentas, often produced at apex into semiterete column bearing anther and stigma; stigma basically 3-lobed or with 3 stigmatic areas, lobes usually confluent in single concave or convex area on ventral side of column, or reduced to 2 discrete lateral lobes on ventral or lateral sides of column, apex of median lobe often transformed into small outgrowth (rostellum) lying between anther and receptive stigmatic areas, portion of rostellum sometimes modified into small viscid disk or viscidium attaching to pollinia or their stipes; ovules numerous and minute, anatropous. Fruits usually capsule, mostly opening laterally by 3 or 6 longitudinal slits. Seeds numerous, usually minute, dust-like, without endosperm; embryo not differentiated.
屬
About 500 genera and more than 24,000 species, cosmopolitan, mainly in tropical and subtropical regions, extending into temperate and subarctic areas; 101 genera with 322 species, 3 subspecies and 5 varieties in Taiwan.
參考文獻
- SU, Horng-Jye, Flora of Taiwan, second edition 5: 729. 2000. (Fl. Taiwan 2nd edit.)
- Dressler, R. L., Dioscorides Press, Oregon. 314pp. 1993.
Listera 雙葉蘭屬
作者
SU, Horng-Jye and HU, Chia-Ying
型態特徵
Terrestrial perennial herbs with fibrous roots and short rhizome. Stems simple, erect, slender, with 2 leaves near middle, usually puberulous, turning into peduncle above leaves, glabrous below leves. Leaves opposite or subopposite, nearly sessile, deltoid, ovate-semiorbicular or orbicular-ovate, acute, mucronate or obtuse at apex, truncate or cordate at base, entire or slightly wavy, mainly 3-7-nerved, with reticulate veinlets. Raceme terminal, with few to many flowers; peduncle and rachis more or less puberulous; bracts ovate-lanceolate or broadly ovate; pedicel and ovary straight or curved, glabrous or slightly puberulous. Flowers usually greenish, sometimes tinged with red-purple on lip; sepals and petals subequal, free, spreading or reflexed, dorsal sepal ovate or lanceolate, lateral sepals obliquely ovate or falcate, petals linear-lanceolate or linear-oblong; lip spreading, undivided or with 2 terminal lobes, sometimes with 2 auricles at base or 2 lateral lobes near base, cuneate, elongate-cuneate or rectangular, entire, incised or ciliate along margins, spurless, disc glabrous or shortly puberulous, flat or sometimes with raised calli or keels, often with shallow nectary of various forms near middle or base; column either short and stout, or slender and elongate, short one nearly sessile, consisting of anther, clinandrium and stigma, without distinct stalk, elongate one consisting of dilated and incurved top, slender neck and slightly dilated stalk at base; anther terminal, nearly erect or inclined, 2-loculed; pollinia 2, unequally 2- partite, soft and mealy; stigma entire, concave under rostellum; rostellum, ovate or rectangular.
