A Taxonomic Study on Dioscorea L. ( Dioscoreaceae ) of Taiwan

山羊百科，林文智老師的植物、山岳、攝影紀錄

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目錄

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A Taxonomic Study on Dioscorea L. ( Dioscoreaceae ) of Taiwan

Chun Kuei Liao　chunkuei.liao@gmail.com
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Abstract

　This thesis is to study habit, tuber, stem, leaf, flower and fruit morphology, phytogeography, and phenology in Dioscorea. Finally, concerns are given to the infrgeneric taxonomy.

　Plants of Dioscorea in Taiwan are scandent vine; underground tuber or rhizome cylindrical, pyriform or spherical; stems terete or quadrangular in cross-section, ridged, or winged, green or violet, pubescent or glabrous or prickly; aerial tuber axillary or absent. Leaves alternate or opposite, simple or palmately compound; simple leaves cordate or ovate-triangular, 3-9 nerved; leaflets of palmately-compound leaves lanceolate or ovate, nerves pinnately; 3-9 nerved; veinlets reticulate; petioles twisted and dilated at base. Flowers usually dioecious, arranged in axillary panicles, racemes, or spikes; male flowers solitary or fasciled on rachis, perianths 6, 2-whorled, tepals mostly similar, stamens 6, sometimes the inner 3 sterile, filaments attached to base of perianths, anthers 2 celled, longitudinally dehiscent, pistillodium rudimentary, present or absent; pistillate flowers solitary on rachis, perianths similar to the staminate, with 0, 3 or 6 staminodia; ovary inferior, trigonous, 3-celled, ovules 2 in each cell; stigmas 3, 2-lobed at apex. Fruit capsulate, tripterous. Seed 2 in each cell, with membranous wing. Flowering period is from April to September. Mostly fruiting from July to November. Most species of the genus in Taiwan are widely spreading in the island. Among the species in Taiwan, two endemic.

　So far, there are 12 species recognized in the genus. Dioscorea alata L. var. purpurea (Roxb.)M. Pouch. is synonymized under D. alata L.；D. codonopsidifolia Kamikoti is synonymized under D. cumingii Prain & Burkill)；D. kaoi Liu & Huang is synonymized under D. collettii Hook. f.)；D. japonica Thunb. var. japonica, D. japonica Thunb. var. pseudojaponica (Hayata) Yamamoto, D. japonica Thunb. oldhamii Uline & Knuth are synonymized under D. japonica Thunb.；D. matsudii Hayata is synonymized under D. cirrhosa Lour. The others consist of D. batatas Decne, D. hispida Dennst, D. esculenta (Lour)Burkill, D. bulbifera L., D. benthamii Prain & Burkill。 D. doryphora Hance and D. formosana Knuth are endemic in Taiwan.

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Dioscorea L., Sp. Pl. 1033. 1753.

A scandent vine; underground tuber or rhizome cylindrical, pyriform or spherical; stem terete or quadrangular in cross-section, ridged, or winged, green or violet, pubscent or glabrous or prickly; aerial tuber axillary or absent. Leaves alternate or opposite, simple or palmately- compound; simple leaves cordate or ovate-triangular, 3-9 nerved; leaflets of palmately-compound leaves lanceolate or ovate, nerves pinnately; 3-9 nerved; veinlets reticulate; petioles twisted and dilated at base. Flowers usually dioecious, arranged in axillay panicles, racemes, or spikes; male flowers solitary or fasciled on rachis, perianths 6, 2-whorled, tepals mostly similar, stamens 6, sometimes the inner 3 sterile, filaments attached to base of perianths, anthers 2 celled, longitudinally dehiscent, pistillodium rudimentary, present or absent; pistillate flowers solitary on rachis, perianths similar to the staminate, with 0, 3 or 6 staminodia; ovary inferior, trigonous, 3-celled, ovules 2 in each cell; stigmas 3, 2-lobed at apex. Fruit capsulate, tripterous. Seed 2 in each cell, with membranous wing.

About 600 species in the world, mostly in tropics, 12 species in Taiwan.

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KEY TO SPECIES

1. Leaves simple

　2. Stems and petioles winged or quadrangular...............1. Dioscorea alata

　2. Stems and petioles neither winged nor anguled

　　3. Stems sinistrose

　　　4. Stems glabrous

　　　　5. pulvinus with a pair spines........................6. Dioscorea collettii

　　　　5. pulvinus auricled-clasped.......................4. Dioscorea bulbifera

　　　4. Stems prickly and with T-shaped villose............9. Dioscorea esculenta

　　3. Stems dextrorse

　　　6. Leaves alternate

　　　　7. Stems glabrous, leaves hastate-triangular...........8. Dioscorea doryphora

　　　　7. Stems prickly, leaves lanceolate...................10. Dioscorea formosana

　　　6. Leaves opposite, sometimes alternate near the base of stems

　　　　8. Leaves lanceolate or elliptic, acute or round at base

　　　　　9. Leaves coriaceous or subcoriaceous, staminate inflorescence paniculiform..........5. Dioscorea cirrhosa

　　　　　9. Leaves chartaceous, staminate inflorescence 1-3 spicate................3. Dioscorea benthamii

　　　　8. Leaves ovate-triangular or hastate lanceolate

　　　　　10. Leaves ovate-triangular, warped inward..............2. Dioscorea batatas

　　　　　10. Leaves narrowly triangular, oblong-triangular, plated........12. Dioscorea japonica

1.Leaves palmately compound

　11. Leaflets 3-7, lateral leaflets narrowly-obovate, oblique-acute at base, male flowers with pedicle.........................7. Dioscorea cumingii

　11. Leaflets 3, lateral leaflets oblique-obovate, round at base, male flowers sessile........................................11. Dioscorea hispida

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List

  1. Dioscorea alata L.
  2. Dioscorea batatas Decne.
  3. Dioscorea benthamii Prain & Burkill
  4. Dioscorea bulbifera L.
  5. Dioscorea cirrhosa Lour.
  6. Dioscorea collettii Hook. f.
  7. Dioscorea cumingii Prain & Burkill
  8. Dioscorea doryphora Hance
  9. Dioscorea esculenta (Lour.) Burkill var. spinosa R. Knuth
  10. Dioscorea formosana R. Knuth
  11. Dioscorea hispida Dennst.
  12. Dioscorea japonica Thunb.
取自"http://plant.climb.com.tw/modules/mediawiki/index.php/A_Taxonomic_Study_on_Dioscorea_L._%28_Dioscoreaceae_%29_of_Taiwan"
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