Ch. 8 Flowers, Fruits and Seeds Flashcards
(18 cards)
Disperal by Water
some fruits contain trapped air, which adapts them to water dispersal
example: sedge seeds are surrounded by inflated sacs
some plants have tseeds and fruits that have thick, spongy pericarps
Describe other less common dispersal methods
- some plants eject seeds (example: some cucumbers, witch hazel)
- geraniums
- humans
Geraniums
have fruit carpels that split away and curls back
seeds are pointed and sensitive to humidity
in sun forms corkscrew shape, drives seed into ground
Seed structure
Ovules develop into seeds
Structures include cotyledons,,,,
Cotyledons
food storage organs that function as seed leaves
Embryo
cotyledons and plantlet
Plumule
embryo shoot
Epicotyl
stem above cotyledon attachment
Hypocotyl
stem below cotyledon attachment
Radicle
tip of embryo that develops into root
Germination
beginning or resumption of seed growth
some require period of dormancy
Describe period of dormancy in germination
- brought about my mechanical or physiological factors (growth inhibiting substances on fruit/seeds)
break this when mechanical abrasion, thawing and freezing, bacterial action, or soaking rains
scarification
artificially breaking dormancy
Describe germination environmental conditions
favorable to have water and oxygen
light or absence
proper temperature range
Imbibing
enzymes in cytoplasm begin to function in germination process after water imbibed
Describe what happens after ripening of fruit containing seed
embryo composed of only few cells when fruit ripens
seed will not germinate until embryo develops
Describe logevity of seeds
varies depening on speices and storage conditions
can be extended at low temps and when kept dry
Vivipary
no period of dormancy, embryo continues to grow while fruit is still on parent
often discouraged in food cultivated for humans
