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.

Thrixspermum 風鈴蘭屬

作者

SU, Horng-Jye

型態特徵

Erect or pendulous epiphytic herbs. Stems either short with few leaves close together, or rather long with many well-spaced leaves. Leaves narrow, usually oblong, flat or conduplicate. Racemes axillary; bracts distichous or spiral. Flowers opening successively, short lived; rarely opening together and long lasting; sepals and petals subequal, ovate to elliptic; lip continuous or jointed to foot of column, concave or saccate at base, 3-lobed, lobes erect from foot of column forming an enclosed sac-like structure, lateral lobes falcate, erect, embracing column, midlobe fleshy, with various trichomes and callosities on disc; column stout, with a distinct broad foot; anther terminal, operculate; pollinia 4, in 2 groups, each divided into unequal halves, or 2 and distinctly sulcate, waxy, attached to a large, broad stipe; stigma entire. Capsules linear-cylindrical.