plant bio exam 2 Flashcards
angiosperm
enclosed seed
ovary
part of flower
ovules are enclosed in ovary
sporpophyte/gametophyte in angiosperms
sporophyte becomes more important and complex
gametophyte becomes reduced, less complex
origin of angiosperms
flower plants appeard in cretaceous suddenly, exploded
ancestors diverged early
archaefructus
seeds in ovaries, found in aquatic habitats
seed plant phylogeny
gymnosperms and angiosperms: seeds
angiosperms: flowers, fruit, double fertilization, non-motile sperm
distinct features of angiosperms
- improved vascular efficiency
- flowers: modified branches and leaves for reproduction
- fruit: ovaries, new forms of seed dispersal and protection
- different life cycle: more efficient fertilization, reduced gametophytes save energy
seedling hypothesis
angiosperms have shorter generation time, rapid growth rate, highly competitive
flower anatomy: four whorls
sepals
pertals
perianth
stamens
carpels
flowers missing one or more whorls: incomplete
sepals
enclose bud and flower
together called calyx
petals
conscipicuous, often colorful
together form corolla
perianth
calyx and corolla together
stamens
male whorl (androecium), anthers
carpels
female whorl (gynoecium), stigma and style
flower architecture: structure
regular: radial symmetry, any line drawn through the flower will produce equal halves
irregular: bilateral symmetry, flower can only be divided into equal halves one way
flower arcihtecture: sex
pistilate (Imperfect)
staminate (imperfect)
monoecious
dioecius
bisexual (perfect)
pistillate
only pistils/carpels, also called carpellate
staminate
only stamens
monoecious
separate staminate/pistillate flower
same plant
dioecious
staminate and pistillate flowers on different plants
bisexual
(Perfect)
flower with both stamens and pistils
androeciu,
stamen: entire male organ, including anther and filament
filament: stalk that supports an anther
anther: pollen-producing organ
pollen sacs are inside anthers
pollen: male gametophyte
meiosis occurs in anthers, forms pollen
pollen=2 celled male gametophyte
generative cell: makes 2 sperm cells
tube cell: produces pollen tube
gynoecium
carpel or pistil: entire female part of the flower
stigma: tip of the carpel that receives pollen
style: supporting stalk
ovary: swollen chamber containing ovules
ovary
protection of seeds against drying and predation
pollen selectivity: pollen must germinate on style, grow correct pollen tube to pass through the style
seed= mature ovule
fruit=mature ovary
ovary positions
superior ovary: ovary above stamens/petals
inferio ovary: over below
hypanthium: fusion of lower whorls into a tube, can be found with multiple ovary positions
embryo sac
female gametophyte
- meiosis occurs in ovule, creates haploid 7-cell embryo sac
- 2 synergids (Direct the pollen tube)
- one egg
- 3 antipodals
- central cell with 2 polar nuclei
advantages of double fertilization
endosperm (Energy reserves) only created at fertilization
conserves resources
no loss of storage organs on unfertilized ovules
not just an energy source for plants
corn kernals=lots of endosperm
coconut water-liquid endosperm
apoximis
reproduction without fusion of sperm and egg
parthenogenesis
development of an embryo from an unfertilized egg
reproduction without fertilization
apomixis, aprthenogeneisis
embryo development can be stimulated by hormones without sperm present
groups that form apomictic seeds include citrus and mango
flowers are clustered
- inflorescence: group or cluster of flowers, flowering branch, derived from modified branches
- bract: leaflike structure at base of inflorescence
- pedical: flower bearing stalk
- peduncle: inflorescence-bearing stalk
inflorescence types
- solitarty: single flwoer at the tip of a branch
- spikeL multiple flowers attached to central axis (catkin)
- raceme: each branch on the central axis ends in a flower
panicle: a branched raceme
infloresence types 2
- umbel: umbrella-like clusters of flowers at same level
- cyme: flat-topped cluster with oldest flowers at center
- corymb: flat topped cluster with youngest flowers at center
infloresence types 3
- head: flowers lack pedicels and are crowded together on a very short axis, asters
- spather and spadix: flowers on fleshy tyube (spadix) found in the arum family
seed vs fruit
seed=mature ovule
fruit=mature ovary
fruits help faciliate seed dispersal
fruit wall
pericarp
- exocarp: outmost
-mesocarp: middle
- endocarp: inner layer, near seeds
- accessory tissues: non-ovary tissue that is part of fruit
dehiscent fruit
split open at maturity
indehiscent fruit
dont split open at maturity
simple fruit
develops from one ovary
compound fruit
develops from more than one ovary
dry dehiscent fruits
legume/pod
capsule
follicle
sillique
legume or pod
dry dehesicnet
- seeds: beans
- pericarp: shell
- fruit arises from a single carpel
not all pods dehisce (open)
capsule
arises from a compound ovary (multiple carpels)
dehisces at top
ex: poppy
follicle
dry dehiscent
- develops from one carpel, opens on one side
ex: magnolia, milkweed
sillique
dry dehiscent
derived from superior ovary, splits into 3 parts at maturity with seeds on central portion
ex: mustard family
dry indehiscent fruits
achene
caryopsis
samara
schizocarp
nuts
achene
dry indehiscnet
one seeded fruit with pericarp and embryo separable
ex: sunflowers, sedges
caryopsis
dry indehiscent
one seeded fruit with pericarp and embryo united
ex: rice, wheat
samara
dry indehiscent
simple fruit with a wing like growth of ovary wall
can have 1-2 seed
ex: maple, elm
schizocarp
dry indehiscent
2 carpels split along midline at maturity
ex: carrot