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Orchidaceae

J. RENZ


Basel, Switzerland.

Cymbidium macrorhizon
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Plants with tuberoids or rhizomes, terrestrial or epiphytic, occasionally saprophytic. Leaves radical or cauline, sometimes reduced to sheaths. Inflorescence one to many-flowered. Flowers zygomorphic, hermaphrodite, usually reversed (resupinated) by torsion of ovary or pedicel. Perianth-segments in 2 whorls: the outer of 3 ± equal segments (sepals), the inner with 2 lateral equal (petals) and one unequal, medium (labellum). Labellum highly modified in shape and coloration, with or without a spur. Style and stamen ± fused to a column (gynostemium). Fertile anthers 1 or 2, the steriles transformed into staminodes near base of column. Fertile stigmas 2-3, usually confluent, a sterile modified into the rostellum, a tissue separating the anther from the fertile stigma. Pollinia 2, sometimes 2-4 parted, or 4, waxy or powdery-granulose, often attached by stalk-like caudicles to 1 or 2 viscid glands (viscidia), which can be free or enclosed in 2 or a single pouch (bursicula). Ovary inferior, sessile or pedicellate; placentation parietal, 1-locular, rarely 3-locular. Fruit a capsule, longitudinally dehiscing by 3 or 6 slits. Seeds tiny, numerous, without endosperm.

Cosmopolitan. Distributed in all climatic zones, except polar and extreme desert regions. Approx. 800 genera with 25,000-30,000 taxa. 47 species, all terrestrial, belonging to 26 genera, are represented in our area.

Acknowledgements: We are grateful to the U.S. Department of Agriculture for financing this research under PL-480. Thanks are also due to the Directors of the various herbaria for providing all the facilities to the author.


1 Labellum slipper-shaped. Fertile anthers two   1 Cypripedium
+ Labellum not slipper-shaped. Fertile anther one   (2)
       
2 (1) Plants saprophytic, leafless or autotrophic with rudimentary leaves. Stem with pale brown or greenish-sheaths   (3)
+ Plants autotrophic, with well-developed green leaves   (7)
       
3 (2) Sepals and petals fused, bell-shaped   18 Gastrodia
+ Sepals and petals free, ± spreading   (4)
       
4 (3) Flowers reversed (resupinated); labellum facing downwards   (5)
+ Flowers not reversed; labellum facing upwards   4 Epipogium
       
5 (4) Rhizome short, with cluster of fleshy roots Labellum green to dark olive-green   2 Neottia
+ Rhizome creeping and branched. Labellum whitish with red spots   (6)
       
6 (5) Rhizome much coralloid-branched. Inflorescence up to 12-flowered. Flowers pendent, small; sepals c.5 mm long   24 Corallorrhiza
+ Rhizome thick, not much branched. Inflorescence 2-5(-8)-flowered. Flowers erect-spreading, large; sepals c. 25 mm long   25 Cymbidium
       
7 (2) Plants with palmate tuberoids   (8)
+ Plants with entire tuberoids, tuberous corms or rhizomes   (10)
       
8 (7) Spur saccate, much shorter than ovary, c. 2 mm long   12 Coeloglossum
+ Spur cylindric, ± as long as ovary, c.8-12 mm long   (9)
       
9 (8) Viscid glands of pollinia enclosed in a pouch(bursicula)   9 Dactylorhiza
+ Viscid glands of pollinia without pouch   10 Gymnadenia
       
10 (7) Plants with entire tuberoids or tuberous corms   (11)
+ Plants with rhizomes   (16)
       
11 (10) Labellum without spur, sometimes ± conically hollowed at base   (12)
+ Labellum with l or 2 spurs   (13)
       
12 (11) Leaves solitary or few, spathulate or lanceolate to linear, contemporaneous with flowers on terminal inflorescence   11 Herminium
+ Leaf 1, petiolate, roundish, cordate at base, appearing after inflorescence-bearing stem scape   19 Nervilia
       
13 (11) Flowers not reversed; labellum facing upwards with 2 spurs   16 Satyrium
+ Flowers reversed; labellum facing downwards with 1 spur   (14)
       
14 (13) Stigma 2 on distinct processes   13 Habenaria
+ Stigma sessile, cushion-like, ± confluent   (15)
       
15 (14) Flowers small, 2-3 mm in diameter. Spur 1 mm long. Anther-canals short. Staminodes filiform-elongate   14 Diphylax
+ Flowers large, 6-10 cm in diameter. Spur more than 8 mm long. Anther-canals ± elongated. Staminodes small, globose   15 Pecteilis
       
16 (10) Labellum divided in hypochile and epichile   (17)
+ Labellum entire or lobed   (18)
       
17 (16) Ovary with short twisted pedicel; flowers ± pendulous   6 Epipactis
+ Ovary ± sessile; flowers erect   5 Cephalanthera
       
18 (16) Base of stem, thickened into leafy corm (pseudobulb)   (19)
+ Base of stem not thickened   (21)
       
19 (18) Plants robust. Leaves 2-4, papery. Flowers showy, lilac or orange-red and white   26 Calanthe
+ Plants slender. Leaves 4-8, membranaceous. Flowers small, unpretentious, green or greenish-lilac   (20)
       
20 (19) Flowers reversed; labellum facing downwards. Column slender, elongate, c. 5 mm   20 Liparis
+ Flowers not reversed; labellum facing upwards. Column very short, cylindric, c.0.5 mm   21 Malaxis
       
21 (18) Roots fusiform-fleshy. Flowers spirally arranged in a single row on twisted axis   17 Spiranthes
+ Roots fibrous. Flowers on a straight axis, not spirally arranged   (22)
       
22 (21) Rhizome elongated into irregularly shaped ovoid or oblong corm. Flowering stem(scape) separate from leaf-bearing stem, both arising from the corm   (23)
+ Rhizome not tuberous. Leaves and flowers on terminal inflorescence   (24)
       
23 (22) Pollinia 2. Leaves produced with (E.graminea) or after the flowers   23 Eulophia
+ Pollinia 4. Leaves produced with the flowers   22 Oreorchis
       
24 (22) Rhizome repent. Leaves ± radical, petiolate, reticulate-nerved. Flowers ± secund   7 Goodyera
+ Rhizome short, ascendent. Leaves cauline, not petiolate, parallel-nerved. Flowers on all sides   (25)
       
25 (24) Leaves two, broad, subopposite in about the middle of the stem   3 Listera
+ Leaves numerous, linear-lanceolate, very much crowded   8 Zeuxine

  • List of lower taxa


     

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