432 PLANT MORPHOLOGY 



Apical cell. A single cell at the tip of a structure from the segments of which all its 



cells are derived. 

 Aplanospore. In various algae, a nonmotile spore with a wall not derived from the 



wall of flio cell in which it is formed. 

 Apocarpous. With s(>parate carpels. 

 Apogamy. Development of an embryo from a cell of the gametophyte other than 



the egg. 

 Apomixis. A condition in which sexual reproduction is replaced by some form of 



asexual reproduction. 

 Apophysis. An enlargement at the base of the capsule of some mosses. 

 Apothecium. A cup-like or disk-like ascocarp. 

 Archegonium. The female sex organ of bryophytes, pteridophytes, and most gymno- 



sperms. 

 Ascocarp. In most ascomycetes, a fruiting body producing asci. 

 Ascogenous hyphae. Hyphae that bear asci. 

 Ascogonium. The female sex organ of ascomycetes. 

 Ascospore. One of the spores borne in an ascus. 



Ascus. In ascomycetes, a sac-like cell in which ascospores are produced. 

 Autoecious. Passing through all stages in the life cycle on the same host, as certain 



rust fungi. 

 Autotrophic. Self-nourishing; capable of making its own food, as a green plant. 

 Auxospore. In diatoms, a reproductive cell formed by the union of two cells or 



asexually. 

 Axil. The upper angle between a leaf or branch and the stem from which it arises. 



Bacillus. A straight, rod-shaped bacterium. 



Basidiocarp. In most basidiomycetes, a fruiting body producing basidia. 



Basidiospore. One of the spores borne on a basidium. 



Basidium. In basidiomycetes, a club-shaped structure that produces basidiospores. 



Basipetal. An order of development in which the youngest structures are at the base 

 and the oldest at the apex. 



Biciliate. Having two cilia. 



Bilocular. Having two locules or cavities. 



Bisporangiate. With microsporangia and megasporangia borne in the same strobilus 

 or flower. 



Bract. A scale borne on a floral axis, especially one subtending a flower or inflores- 

 cence. 



Calyptra. In bryophytes and pteridophytes, a covering developed from the venter 



of the archegonium and surrounding the sporophyte, at least when young, and in 



some mosses later carried on top of the capsule as a hood. 

 Calyptrogen. That part of the embryonic tissue of a root tip from which the rootcap 



is developed. 

 Calyx. The sepals of a flower, collectively; the outer whorl of perianth parts. 

 Cambium. A lateral meristem consisting of a layer of cells giving rise to secondary 



tissues, particularly xylem and phloem, in many roots and stems. 

 Campylotropous. Having the ovule turned so that the base and apex are close 



together. 

 Capillitium. A network of delicate threads, as in the sporangium of a myxomycete. 

 Capsule. In bryophytes, any closed vessel containing spores; in angiosperms, a dry, 



dehiscent, many-seeded fruit derived from a compound pistil. 



