Annuals vs Perennials
Monocots vs Dicots
Types of Plant Life
Xeriphates: Plants such as cacti, that are adapted to an arid environment.
Mesophytes: Plants adapted and survive in an environment with a moderate amount of water.
Hydrophytes: Plants constantly exposed to water (aquatic plants).
The leaf of a plant serves several important functions. Leaves are the chief organs of photosynthesis, a process in which plants are capable of converting light energy into organic food. Most leaves are arranged on the stem in such a way as to receive maximum sunlight and cast minimum shadows on other leaves. Leaves are the major organs responsible for gas exchange between the plant and its surrounding atmosphere. The gases typically move through small openings in the leaf known as stomata or stomates. Water, in a vapor form, also passes through these openings, a process known as stomatal transpiration.
The stomata are openings in the epidermis surrounded by two specialized epidermal cells, the guard cells, which by changes in shape bring about the opening and closure of the pore. The guard cells are normally kidney-bean shaped cells that contain chloroplasts.
The stomata may be located on the upper leaf surface only, lower leaf surface only, or both the upper and lower leaf surfaces.
Number and distribution of stomata vary considerably if grown under different environmental conditions, such as in a dry field or a moist greenhouse. On the other hand, the sizes of stomata are fairly constant for species.
Monocots typically have approximately a 1:1 ratio of stomata on the upper and lower epidermis.
Dicots typically have the greatest number of stomata
on the lower epidermis, with stomata often absent
on the upper epidermis.
Plant Self- Defense
Plants were first aquatic, then there were mosses
Bryophytes : the non-vascular plants
Gymnosperms and conifers
And then Angiosperms
How cacti adapt