台灣山螞蝗族植物花粉的研究

Abstract

本文以台灣山螞蝗族(Desmodieae)中十二個屬三十四種植物的花粉為材料，應用光學及電子顯微鏡來觀察花粉外部形態及內部層次構造中所展現的特徵差異，發現這一族植物的花粉形態變異很大，雖然都是三溝孔粉，但外壁花紋及層次結構在屬間與種間卻各異其趣。 山螞蝗族植物之花粉依目前所觀察的結果，由外部形態及層次結構約可分為六類。第一類型：外壁粗網紋，明顯雙緣溝，溝緣外壁無雕紋，孔處有孔蓋的覆蓋，例如彎龍骨屬(Campylotropis)、雞眼草屬(Kummerowia)及胡枝子屬(Lespedeza)。第二類型分兩種亞型如：(A)外壁皆為粗網紋，雙緣溝，溝緣外壁雕紋微細穿孔，溝孔處有細顆粒覆蓋，例如木山螞蝗屬(Dendrolobium)、銳葉小槐花(Desmodium caudatum)、排錢樹屬(Phyllodium)及葫蘆茶屬(Tadehagi)；(B)外璧細網紋，壁層沒有微細管道及柱間顆粒，最內層厚度大增，例如多花山螞蝗(Desmodium multiflorum)、腎葉山螞蝗(Desmodium renifolium)、波葉山螞蝗(Desmodium sequax)。第三類型：外壁為瘤狀突起，蓋頂明顯半圓紋，例如鍊莢豆屬(Alysicarpus)、南美山螞蝗(Desmodium intortum)及蝦尾山螞蝗(Des. scorpiurus)，在鍊莢豆屬花粉粒可見到溝孔處為粗顆粒覆蓋，而兩種山螞蝗則缺乏此構造。第四類型：外壁微細穿孔或具有輕微的網狀散條紋，例如鐘萼豆(Codariocalyx)、變葉山螞蝗(Desmodium heterophyllum)、小葉山螞蝗(Des. microphyllum)、小山螞蝗(Des. podocarpon subsp. oxyphyllum)、蠅翼草(Des. triflorum)、密子豆屬(Pycnospora)。第五類型：外壁皆細網散條紋，基層不連續，最內層厚度與蓋頂相當，圓柱層已見退化，例如鋪地蝙蝠草(Christia obcordata)、大葉山螞蝗(Desmodium gangeticum)、假地豆(Des. heterocarpon var. heterocarpon)、直毛假地豆(Des. heterocarpon var. strigosum)、絨毛葉山螞蝗(Desmodium velutinum)。第六類型：外壁具微細穿孔，圓柱被柱間顆粒取代，基層消失，例如兔尾草屬(Uraria)。 分類學者比較各屬間之外部形態，將山螞蝗族又分為三個亞族，台灣僅?兩個亞族--即山螞蝗亞族及胡枝子亞族，但是由花粉形態上的差異來看，反而在其間尋到一些相似性，可能是演化的過程中適應環境而在外部形態上?生變化，內部構造如花粉粒卻未及改變而保持相似的植物特徵。

The pollen morphology of twelve genera thirty four species belonging to plants of Desmodieae in Taiwan was studied with light microscopy, scanning electron microscopy and transmission electron microscopy. The great varieties of pollen morphological characters among plants of Desmodieae were observed. According to pollen morphology and exine stratification, we can classify the Desmodieae into six types: Type I: It is characterized by its exine coarsely-reticulate, distinctly marginate and tectum psilate on margin of colpi with operculum. e.g. Campylotropis, Kummerowia and Lespedeza Type II: This type is subdivided as subtype(A): It is characterized by its exine finely-reticulate, without microchannel and granular interstitium, and endexine thicker than ectexine. e.g. Desmodium multiflorum, Des. sequax and Des.velutinum subtype(B): It is characterized by its exine reticulate, marginate, tectum microperforated and colpi finely-granulate. e.g. Dendrolobium, Desmodium caudatum, Phyllodium and Tadehagi Type III: It is characterized by its exine coarsely-granulate and weakly rugulate. e.g. Alysicarpus, Desmodium intortum, and Des. scopiurus. but Alysicarpus posseses the operculum the other two Desmodieae species are absent. Type IV: It is characterized by its exine microperforated or weakly rugulate and foot layer reduced. e.g. Codariocalyx, Desmodium heterophyllum, Des. microphyllum, Des. podocarpon subsp. oxyphyllum, Des. triflorum and Pycnospora Type V: It is characterized by its exine finely-reticulate, foot layer discontinuous, and endexine as thick as tectum. e.g. Christia obcordata, Desmodium gangeticum,, Des. heterocarpon var. heterocarpon, Des. heterocarpon var. strigosum, Des. renifolium and Des. velutinum. Type VI: It is characterized by its exine microperforated, columellae replaced by granular interstitium and without foot layer. e.g. Uraria The Desmodieae plants are taxonomically recognized as 3 subtribes all over the world, but there are only two subtribes in Taiwan, i.e., Desmodiinae and Lespedezinae. Although they are so different, we can find some similarities of pollen morphology between them. It was presumed that the evolutionary patterns of Desmodieae plants are different. They changed the external features, but retained the internal characters such as pollen features.