单词	heterosporous
释义	heterosporous /ˌhetəˈräspərəs/ /-ərəˈspôrəs / adjective Biology Producing two different kinds of spores.Both of these genera are heterosporous, meaning that each species produces two distinctly different types of spores: microspores and megaspores.... Therefore, improved sampling and a better understanding of the morphology of fossils with affinities to these families are necessary to understand the origin and evolution of the heterosporous fern clade. Some of the large sphenophyte trees of the Paleozoic were heterosporous, producing large megaspores and small microspores, and probably retaining the megaspore in the strobilus. Derivatives heterospory noun ... The Order Isoetales and Lepidodendrales are sometimes included in the Subclass Ligulatae - defined by the presence of ligules, heterospory, and endospory. Since the ‘seed habit’ begins with the reduction to a single functional megaspore in each megasporangium, heterospory seems like a logical intermediate step. According to this argument, heterospory was the intermediate between homosporous free-sporing reproduction and the retained endosporic gametophyte of the seed habit.
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