Azollaceae
Azollaceae A specialized family of free-floating, aquatic ferns of uncertain affinities. The branched stems bear roots, and 2-lobed, overlapping leaves. Sori bear either microsporangia or megasporangia. The megasporangia are each provided with floats; microspores are numerous and grouped together into ‘massulae’ which bear barbed hairs (glochidia) that hook on to the megaspores. The leaves have a basal cavity inhabited by a cyanobacterium (Anabaena azollae) which fixes nitrogen. There is 1 genus, Azolla, with 6 species, of tropical and warm temperate distribution in America and Asia. They are not native in Europe, but are naturalized there.
More From encyclopedia.com
Encyclopedia.com. , bear1 / be(ə)r/ • v. (past bore / bôr/ ; past part. borne / bôrn/ ) [tr.] 1. (of a person) carry: he was bearing a tray of brimming glasses. ∎ have o… Teddy Bear , Background
Most people born in this century have probably encountered teddy bears during their lives, for the teddy bear was developed around the tur… Bearing , bear·ing / ˈbe(ə)ring/ • n. 1. [in sing.] a person's way of standing or moving: a man of precise military bearing. ∎ the way one behaves or conducts… Polar Bear , polar bear, large white bear, Ursus maritimus, formerly Thalarctos maritimus, of the coasts of arctic North America, Asia, and Europe. Polar bears us… Ball Bearing , Background
Ever since man began to need to move things, he has used round rollers to make the job easier. Probably the first rollers were sticks or l… Grizzly Bear , The grizzly bear (Ursus arctos ), a member of the family Ursidae, is the most widely distributed of all bear species . Although reduced from prehisto…
You Might Also Like
NEARBY TERMS
Azollaceae