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Chlorophytes are eukaryotic organisms composed of cells with a variety of coverings or walls, and usually a single green chloroplast in each cell. [4] They are structurally diverse: most groups of chlorophytes are unicellular, such as the earliest-diverging prasinophytes, but in two major classes (Chlorophyceae and Ulvophyceae) there is an evolutionary trend toward various types of complex ...
Life forms: (1) Phanerophyte, (2; 3) Chamaephyte, (4) Hemicryptophyte, (5; 6) Geophyte, (7) Helophyte, (8; 9) Hydrophyte. Therophyte and epiphyte are not shown. The Raunkiær system is a system for categorizing plants using life-form categories, devised by Danish botanist Christen C. Raunkiær and later extended by various authors.
The flowering stalk, which appears a few weeks before flowering, is narrow, but may reach nearly 3 m (9.8 ft) in height. It is composed of numerous, very sticky stalklets bearing up to 600 flowering heads about 2.5 cm (31 ⁄ 32 in) in diameter, each containing 500 individual flowers. Each head has about a dozen pink to maroon petal-like ray ...
By another definition, however, maximum life span corresponds to the age at which the oldest known member of a species or experimental group has died. Calculation of the maximum life span in the latter sense depends upon the initial sample size. [1] Maximum life span contrasts with mean life span (average life span, life expectancy), and longevity.
In biology, a biological life cycle (or just life cycle when the biological context is clear) is a series of stages of the life of an organism, that begins as a zygote, often in an egg, and concludes as an adult that reproduces, producing an offspring in the form of a new zygote which then itself goes through the same series of stages, the ...
The only known freshwater bivalve with a symbiotic relationship are in the genus Anodonta which hosts the chlorophyte Chlorella in the gills and mantle of the host. [41] In bivalves, photosymbiosis is thought to have evolved twice, in the genus Anodonta and in the family Cardiidae. [ 42 ]
The distinctions between the genera are artificial, since they do not correspond with monophyletic groupings; [7] occasionally, Ankistrodesmus is found as single cells. [6] Other similar genera include Keratococcus and Elakatothrix. [3] Identification of species chiefly depends on details of the size and shape of cells. [2]
Biennial – plants that need two growing seasons to complete their life cycle, normally completing vegetative growth the first year and flowering the second year. Herbs – see herbaceous. Herbaceous – plants with shoot systems that die back to the ground each year – both annual and non-woody perennial plants.