lab 5 terms Flashcards
mucigel
a polysaccharide secreted by the outermost cells of the root cap; for protection from desiccation and for lubrication of the root tip to ease penetration into the soil as the root grows
fibrous root system
the roots of a plant consisting of several fairly equal-sized adventitious roots growing from the base of the stem; characteristic of monocots
adventitious root
a root that grows from any part of the plant other than the root system
aerial root
a root that grows above ground
prop root
adventitious, aerial roots arising from the stem and helping to support the stem; common in monocots such as corn
pneumatophore (aerating root)
modified roots from plants growing in very wet conditions that grow up out of the water to obtain oxygen
haustorial root
a modified aerial root that is capable of penetrating the tissues of another plant to obtain food and water
propagative root
modified roots with shoot buds which function in asexual reproduction
storage root
fleshy roots modified to store large amounts of food or water
root nodules
swelling on the roots of legumes inhabited by nitrogen-fixing bacteria
exodermis
the outer layer, one or more cells thick, of the cortex of some roots (e.g. ranunculus); can secrete suberin and function as the epidermis if it is damaged
storage parenchyma
parenchyma cells within the root cortex which store large amounts of starch from the sugar produced during photosynthesis
starch grains
insoluble carbohydrate molecules; the main food storage product of plants
endodermis
a single layer of cells, usually the innermost layer of the cortex of roots (found in some stems and leaves such as pine) which forms a sheath around the stele; the cells have a Casparian strip within their radial and transverse cell walls
stele
the central cylinder located interior to the cortex of roots and stems; composed of the xylem, phloem, and pericycle; may have a pith, as seen in monocots
