Lycopodiaceae

Members of Lycopodiaceae are not spermatophytes and so do not produce seeds. Instead they produce spores, which are oily and flammable, and are the most economically important aspects of these plants. The spores are of one size (i.e. the plants are isosporous) and are borne on a specialized structure at the apex of a shoot called a strobilus (plural: strobili), which resembles a tiny battle club, from which the common name derives. Members of the family share the common feature of having a microphyll, which is a "small leaf with a single vein, and not associated with a leaf gap in the central vascular system." In Lycopodioideae monoplastidic meiosis is common, whereas polyplastidic meiosis is found in Lycopodielloideae and Huperzioideae. ==Taxonomy==

The family Lycopodiaceae is considered to be basal within the Lycopodiopsida (lycophytes). One hypothesis for the evolutionary relationships involved is shown in the cladogram below. }} There are about 400 known species in the family Lycopodiaceae. Genera , the Checklist of Ferns and Lycophytes of the World recognized the following genera as members of Lycopodiaceae. }} ==Distribution and habitat ==

The members of Lycopodiaceae are terrestrial or epiphytic in habit and are most prevalent in tropical mountain and alpine environments. == Evolution ==

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 syntenic blocks (remaining in the same arrangement). They have also gone through independent whole genome duplications. In most plants the majority of duplicate genes are lost relatively quickly through diploidization, but in this group both sets of genes tends to be retained with relatively few alterations, even after hundreds of millions of years after the duplication event. Spores indicate that the crown group of Lycopodiaceae had emerged by the Triassic-Jurassic boundary, around 200 million years ago, with a member of the crown group of Lycopodioideae known from the Early Cretaceous of China. ==Uses==

• The running clubmosses (Diphasiastrum) have long been used as greenery for Christmas decoration. • The spores have long been used as a flash powder. See Lycopodium powder. • The spores have been used by violin makers for centuries as a pore filler. • In Cornwall, club mosses gathered during certain lunar phases were historically used as a remedy for eye disease. == References ==