Question

1. Describe the differences between (be detailed):

1. Bryophytes
2. Ferns
3. Gymnosperms
4. Angiosperms

Answer 1

a. Bryophytes ; In all bryophytes the photosynthetic phase of the life cycle is the haploid, gametophyte generation rather than the diploid sporophyte; bryophyte sporophytes are very short-lived, are attached to and nutritionally dependent on their gametophytes and consist of only an unbranched stalk, or seta, and a single, terminal sporangium. And, bryophytes never form xylem tissue, the special lignin- containing, water-conducting tissue that is found in the sporophytes of all vascular plants.

b. Ferns ; A fern plant generally consists of one or more fronds (the leaf of the fern) attached to a rhizome. A rhizome is a specialized, root-like stem. In most temperate-zone species of ferns, the rhizome is subterranean and has true roots attached to it. Fronds are generally connected to the rhizome by a stalk, known technically as the stipe. The structures of the frond, rhizome, and stipe are important characteristics for species identification.

c. Gymnosperms ; Any vascular plant that reproduces by means of an exposed seed, or ovule. The seeds of many gymnosperms (literally “naked seed”) are borne in cones and are not visible until maturity. Taxonomists recognize four distinct divisions of extant (non-extinct) gymnospermous plants—Coniferophyta, Cycadophyta, Ginkgophyta, and Gnetophyta—with 88 genera and more than 1,000 species distributed throughout the world.

d. Angiosperms ; Despite their diversity, angiosperms are clearly united by a suite of synapomorphies (shared, derived features) including a) ovules that are enclosed within a carpel, that is, a structure that is made up of an ovary, which encloses the ovules, and the stigma, a structure where pollen germination takes place, b) double fertilization, which leads to the formation of an endosperm (a nutritive tissue within the seed that feeds the developing plant embryo), c) stamens with two pairs of pollen sacs, d) features of gametophyte structure and development, and e) phloem tissue composed of sieve tubes and companion cells . All available evidence strongly rejects hypotheses of more than one evolutionary origin of extant angiosperms.