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.

Cheirostylis 指柱蘭屬

作者

LEOU, Chong-Sheng

型態特徵

Small terrestrial herbs without normal roots. Stems decumbent below and rhizome-like, ascending or erect and leafy above; rhizomes often moniliform, with many constricted nodes, internodes with 2 to several rows of root-ridges, longitudinally grooved between root-ridges, ridges densely covered with long hairs; erect stems short or long, sometimes slightly swollen at internodes. Leaves few to many, congested near base of stem or more evenly cauline, ovate, membranaceous, 5-nerved, petioles sheathed at base. Inflorescence terminal, pedunculate or rarely sessile, racemose. Flowers few to many, small, resupinate; sepals membranaceous, connate for more than half their length forming a tube; petals free, falcate, appressed to sepal tube; lip often tripartite and joined with column at base, rarely undivided and attached to base of column, hypochile saccate, bearing 2 or 2 rows of papillae on lateral side, mesochile clawed, epichile protruding beyond sepal tube, dilated and bilobed, lobes dentate or pectinate at margins; column erect, with 2 appendages on ventral side, appendages (stylids) subequal in length and parallel to rostellum, rarely reflexed or low and flange-like; anther terminal on dorsal side of column, erect, 2-celled; pollinia 2, sectile, clavate or cylindrical, with a slender stalk attached to a tegula stipe, stipe as long as or longer than pollinia; stigma 2, on lateral sides of column , near base of restellum; rostellum erect, triangular, deeply cleft into long arms, with long or short viscidium on ventral side.