morphology of flowering plants Flashcards
describe roots
Underground, cylindrical,non-green part of plant, lacks nodes, buds, leaves
nature of roots
positively geotropic, negatively phototropic
describe tap root system
primary root elongates from radicle and differentiates into lateral, secondary, tertiary, etc roots
example of tao root systems
most dicots ; mango, kidney beans
describe fibrous roots
primary root is short lived and instead is replaced by number of fibrous roots that originate from base of stem
examples of fibrous roots
wheat, coconut, corn, maize
describe adventitious roots
when roots originate from any other part of plant other than radicle
examples of adventitious roots
grass, monstera, banyan
main functions of roots
absorption of water and minerals from soil, Anchorage to plant, storage of food materials, synthesis lf plant growth hormones
apex of root is covered by ; function
a thimble like structure called root cap ; protects the tender apex of root top
describe root cap
multicellular, parenchymatous cells
below the root cap is the
region of meristematic activity
decribe cells of meristematic region
thin walled, dense protoplasm, small, undergo repeated division
region proximal to region of meristematic region
region of elongation
region of elongation is responsible for
growth of roots in length
storage roots
primary roots modify to assume shapes and store food
examples
beet, radish, carrot, turnip, sweet potato
respiratory roots
some plants like rhizophora, growing in swampy areas, roots rise upwards and out of the ground for respiration. called pneumatophores
examples pf respiratory roots
rhizophora, mangroove trees
prop roots
roots that arise from branches to provide mechanical support
examples of prop roots
banyan tree,
stilt roots
roots arising from lower nodes of stem for anchorage of main axis and enter soild obliquely
examples of stilt roots
sugarcane, maize
describe stem
ascending part of plant, green, bearn nodes, internodes, buds, leaves, flowers, fruits
stem arises from
plumule part of embryo of germinating seed
portion from which leaves arise in stem
nodes
portion of stem between two nodes
internodes
bud is defined as
immature, young, under-developed, compact shoot
two types of buds are
terminal, axillary budd
terminal bud is
present at the tip of stem ; growth of bran hes is accomplished through terminal bud
terminal bud is also called as
apical bud
axillary bud is
present between the leaf that makes an angle with the stem
axillary bud is also called as
lateral bud
function of stems
stem bears, leaves, flowers, fruits, conduction of water and minerals and photosynthates, storage lf food, protection, vegetative propagation
modifications of stem
Underground stem, stem tendrils, thorns, sub-aerial weak stem, aerial stems, cladode
Underground stem is divided into
rhizome, tuber, corm, bulb
describe underground stem
stem is modified to penetrate the soil and act as a storage organ in some planst and organ of perennation during unfavorable conditions
describe rhizhome
it grows parallel or horizontal to soil surface, bears nodes, internodes and leaves
examples of rhizome
ginger , banana, turmeric, ferns
describe tuber
terminal portion of underground stem that swells up to act as a storage organ for food
examples of tuber
potato, helianthus tuberosus(jerusalem artichoke)
describe corm
grows vertically, bears nodes, internodes, leaves
examples of corm
colocasia, colchicum, crocus, gladiolus, amorphophallus(zaminakand)
describe bulb
stem is reduced, disc shaped, concentric circles of leaves surround the bud, inner leaves are fleshy and edible and the outer ones are dry
examples lf bulb
lily, onion, garlic
describe stem tendrils
axillary buds modify to form tendrils that provide support and anchorage.
tendrils are long slender thread like structures that wrap around nearby stem for support
examples of stem tendrils
grape vine, gourds( watermelon, cucumber, pumpkin)
describe thorns
axillary buds modify and lose their ability to grow and form pointed woody structures called thorns ; they prevent browsing animals to feed on the plants
examples lf thorns
citrus and Bougainvillea
sub-aerial weak stem is divided into
suckers, runners, offsets, stolons
describe offsets
the stem grows laterally and bear internodes, and nodes, an offset/rosette of leave grow from the nodes and a tuft of roots below the stem
examples of offsets
pistia, eichhornia
describe suckers
stem grows laterally and branches grow under the soil to some distance and then grow out obliquely to form aerial branches
examples of suckers
banana, Pineapple, chrysanthemum