松杉类裸子植物的大孢子叶球理论评述

Review on the megastrobilus theories of conifers

系统评述了迄今为止在裸子植物球果类种鳞形态学本质方面存在过的各种观点及研究进展。将这些观点归纳为 7大类 :(1 )Delpino和Penzig等主张种鳞为叶性器官的叶性说 ;(2 )Sachs和Eichler认为种鳞相当于叶舌的叶舌说 ;(3)Bessey认为种鳞不过是胚珠合点端增生的结果的独特结构说 ;(4)Kubart等提出生胚珠构造的假种皮学说 ;(5)Arber的半枝学说 ;(6)Dupler的珠被说认为红豆杉类胚珠的肉质化部分为珠被性质的构造 ;(7)由Schleiden和Braun提出并由Florin等发展的枝性说则以充分的证据论证了种鳞的枝性本质。关于球果类裸子植物种鳞的性质和来源 ,本文作者赞同Florin枝性本质的论述 ;但对该构造现存式样的组成和演化过程 ,笔者认为该构造是在个体发育中不甚分化的专营生殖的枝性复合构造 ,由早期裸子植物次级生殖枝及其相关构造经过系统发育变态、融合演化形成。

Theories about the seed scale of conifers are reviewed. The classical Foliar Nature theory of Delpino & Penzig suggested that the ovuliferous scales in pine are homologous to the foliar appendages of a cone axis. The Ligular theory of Sachs & Eichler maintained that the seed scale of conifers is comparative to a ligule, because it grows out from a foliar organ, namely the bract. Bessey thought that the seed scale of conifers is the combined outgrowths of an ovule from its chalazal end, which is a sui generis structure thereafter. Kubart misproposed the aril nature of the ovuliferous structure in Juniperus. Arber’s Partial-Shoot theory held that an ovuliferous scale is homologous to a simple and limited shoot (a partial shoot) based on the Telome theory, but Meeuse remarked that the Telome theory was abused here. Dupler emphasized the integumental nature of the ovuliferous scales in taxads. The Brachyblast theory of Braun has increasingly convinced the present botanists on account of excellent studies from teratology, anatomy, ontogeny and palaeobotany. Based on the established evidence from teratology, anatomy, ontogeny and palaeobotany, the present authors believe that the seed scales of living conifers may have evolved from the secondary reproductive branches of the early conifers by phylogenetic metamorphism and fusion, and little differentiation during ontogeny in the living representatives.