EMBRYOPHYTE SPORES:

Certain plants posses vascular tissue for the internal transport of liquids, but they do not reproduce by seeds. Instead, they produce a variety of microscopic unicellular reproductive cells called spores. These spores are haploid and develop into gametophytic plants which may be male (antheridial) or female (archegonial) or both. Fertilization (and the beginning of the sporophyte [diploid] generation} begins when the sperm from the antheridia swims to the egg in the archegonia. Some plants produce only one kind of spore (homosporous) but others produce a large megaspore which develops into the female gemetophyte, and a small microspore, which produces the male gametophyte. Triangular (trilete) forms are more common than oval (monolete) ones. The surface sculpture is various, and many forms posses a covering perine. Examples include liverworts, club mosses, horse tails, ferns, and many extinct forms.

Examples

Sculpturing is various, for both monolete or trilete spores. Germination accomplished by rupture through the laesura, a reinforced (margo) opening on the proximal face of the spore. Germination results in the growth of the gametophyte (haploid), which produces male and female gametes. Fertilization, accomplished through motile sperm results in the sporophyte (spore producing, diploid) generation of the plant, which is generally much larger than the gametophyte generation.

liverworts (Riccia)

club mosses (Selaginella)

ferns (Cystopteris

horse tails (Equisetum)

Osmunda
 

and many extinct forms


Owen Davis 12/99