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.

Zeuxine 線柱蘭屬

作者

LEOU, Chong-Sheng

型態特徵

Terrestrial or rarely epiphytic herbs. Stem erect or ascending from short or long creeping base, fleshy, nodose, leafy upward. Leaves petiolate and sheathing at base or rarely sessile, chartaceous or membranaceous, green or with white stripe along midrib, fleshy and spreading or more often withered and pendent at anthesis. Inflorescence terminal, peduncle often hairy, sheathed below; spikes with few to many flowers; bracts membranaceous, often hairy, rarely glabrous. Flowers resupinate; ovaries hairy or glabrous; sepals free, hairy or glabrous, dorsal one concave, erect, lateral ones hardly spreading, rarely patent; petals thin, appressed to dorsal sepal forming hood; lip either undivided and entire or 3- lobed at apex, or more often tripartite, hypochile saccate, bearing papillae of varied shapes within, mesochile claw-like, without lateral flange, epichile dilated and bilobed; column stout, erect, dimidiate cylindrical or subcylindrical, lateral side broad and smooth or thin and wing-like, ventral side with pair of keels or wings, or transversely elevated low ridge; anther terminal on dorsal side of column, 2-celled; pollinia 2, ovoid-clavate or cylindrical, each 2-partite, sectile, joined together or separated at tapered ends and attached to large tegula stipe, stipe subequal in length to pollinia or longer, narrower or broader; stigma 2, on lateral or ventral side of rostellum; restellum long, cleft, often bent to front; viscidium on ventral side of tegula stipe.