Orchidaceae

蘭科

APG 4

Orchidaceae 蘭科

特徵描述

屬列表

標本列表

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.

Cymbidium 蕙蘭屬

作者

SU, Horng-Jye

型態特徵

Terrestrial, epiphytic or rarely saprophytic herbs with basal pseudobulbs of a few internodes. Roots thick, with whitish velamen, 5-10 mm in diam. Pseudobulbs ovoid or clavate, bearing tuft of leaves, covered with sheaths or overlapping leaf-bases. Leaves alternate or fascicled, linear or oblong-lanceolate, erect or curved, entire or minutely serrulate, coriaceous or membranaceous, never plicate, petiolate or not. Peduncle arising from lower part or base of pseudobulb, erect, arched or pendulous, with solitary flower or many racemose flowers; bracts shorter or longer than pedicel and ovary. Flowers fairly large, often fragrant; sepals nearly equal, free and spreading, linear lanceolate, oblong or lanceolate; petals nearly same length or shorter than sepals, oblong or ovate oblong, not widely spreading, often covering column and lip; lip hinged to base of column or basally united with base and sides of column, more or less 3-lobed, lateral lobes often erect and embracing column, midlobe usually recurved downwards, disc with 2 longitudinal keels; column rather long, semiterete, apex enlarged; anther terminal, operculate, 2-celled; pollinia 2, deeply cleft, or 4 in 2 superposed pairs, joined by short caudicle to broad common viscidium; stigma entire. Capsules usually fusiform.