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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 two different sizes: the larger spore (megaspore) in effect functioning as a "female" spore and the smaller (microspore) functioning as a "male".
The plants have an underground sexual phase that produces gametes, and this alternates in the lifecycle with the spore-producing plant. The prothallium developed from the spore is a subterranean mass of tissue of considerable size, and bears both the male and female organs ( antheridia and archegonia ). [ 6 ]
All vascular plants are sporophyte dominant, and a trend toward smaller and more sporophyte-dependent female gametophytes is evident as land plants evolved reproduction by seeds. [7] Those vascular plants, such as clubmosses and many ferns, that produce only one type of spore are said to be homosporous.
The use of C. richardii in genetic research studies has been valuable to understanding fern and plant evolution as a whole, and in 2019 "C-fern" became the first homosporous fern to have its genome partially assembled, thus acting as a reference genome to which other ferns can be compared. [9]
[2] [3] Lycophytes were some of the dominating plant species of the Carboniferous period, and included the tree-like Lepidodendrales, some of which grew over 40 metres (130 ft) in height, although extant lycophytes are relatively small plants. [4] The scientific names and the informal English names used for this group of plants are ambiguous.
Most non-vascular plants, as well as many lycophytes and most ferns, are homosporous (only one kind of spore is produced). Some lycophytes, such as the Selaginellaceae and Isoetaceae , [ 7 ] : 7 the extinct Lepidodendrales , [ 8 ] and ferns, such as the Marsileaceae and Salviniaceae are heterosporous (two kinds of spores are produced).
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 ...
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.