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Heterospory evolved due to natural selection that favoured an increase in propagule size compared with the smaller spores of homosporous plants. [ 2 ] Heterosporous plants, similar to anisosporic plants [ clarification needed ] , produce two different sized spores in separate sporangia that develop into separate male and female gametophytes.
Lycopodiopsida is a class of vascular plants also known as lycopsids, [1] lycopods, or lycophytes. Members of the class are also called clubmosses , firmosses , spikemosses and quillworts . They have dichotomously branching stems bearing simple leaves called microphylls and reproduce by means of spores borne in sporangia on the sides of the ...
Some lycophytes are homosporous while others are heterosporous. [5] When broadly circumscribed , the lycophytes represent a line of evolution distinct from that leading to all other vascular plants , the euphyllophytes , such as ferns , gymnosperms and flowering plants .
Lycopodiaceae (homosporous lycophytes) split off from the branch leading to Selaginella and Isoetes (heterosporous lycophytes) about ~400 million years ago, during the early Devonian. The two subfamilies Lycopodioideae and Huperzioideae diverged ~350 million years ago, but has evolved so slowly that about 30% of their genes are still in ...
Most heterosporous plants there are two kinds of sporangia, termed microsporangia and megasporangia. Sporangia (clustered in sori) on a fern leaf Equisetum arvense strobilus cut open to reveal sporangia. Sporangia can be terminal (on the tips) or lateral (placed along the side) of stems or associated with leaves.
The Marchantiophyta (/ m ɑːr ˌ k æ n t i ˈ ɒ f ə t ə,-oʊ ˈ f aɪ t ə / ⓘ) are a division of non-vascular land plants commonly referred to as hepatics or liverworts.Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information.
The pollen grains, which are the male gametophytes, are reduced to only a few cells (just three cells in many cases). Here the notion of two generations is less obvious; as Bateman & Dimichele say "sporophyte and gametophyte effectively function as a single organism". [8] The alternative term 'alternation of phases' may then be more appropriate ...
Vascular plants are either homosporous (or isosporous) or heterosporous. Plants that are homosporous produce spores of the same size and type. Heterosporous plants, such as seed plants, spikemosses, quillworts, and ferns of the order Salviniales produce spores of