植生专有名词定义题2(植物学期复习资料）.docVIP

Please give definition of the following botanical terms 06A Endomembrane system Collectively, the cellular membranes that form a continuum (plasma membrane, tonoplast, endoplasmic reticulum, Golgi bodies, and nuclear envelope). Crossing over The exchange of corresponding segments of genetic material between the chromatids of homologous chromosomes at meiosis. Casparian strip A bandlike region of primary wall containing suberin and lignin; found in anticlinal-radial and transverse-walls of endodermal and exodermal cells. 1.4 Sporic meiosis Meiosis resulting in the formation of haploid spores by a diploid individual, or sporophyte; the spores give rise to haploid individuals, or gametophytes, which eventually produce gametes that fuse to form diploid zygote; the zygotes, in turn, develop into sporophytes; this kind of life cycle is known as an alternation of generations. 1.5 Basidiospores Spores of the basidiomycota, produced within and borne on a basidium following nuclear fusion and meiosis. 1.6 Type specimen Usually a dried plant specimen housed in an herbarium; selected by a taxonomist to serve as the basis for comparison with other specimens in determining whether they are members of the same species or not. 1.7 Unilocular sporangium The unilocular reproductive structures which were produced by diploid sporophytes to form haploid zoospores that germinate to produce gametophytes, meiosis firstly takes place within the unilocular sporangia. 1.8 Sorus A group or cluster of sporangia or spores in ferns. 1.9 Ovuliferous scales In certain conifers, the appendage or scalelike shoot to which the ovule attached. 1.10 Parietal placentation Of placentation, with placentas positioned on the wall of a unilocular compound ovary and ovules attached to the outer wall of the ovary instead of the axis and pointing inwards. 06B 1.1 Protoplast The protoplasm of an individual cell; in plants, the unit of protoplasm inside the cell wall. 1.2 Chiasmata The