Angiosperms

Question 1

angiosperms: key evolutionary innovations

Answer 1

• improved conducting tissue (vessel elements)
• efficient “leaf plumbing” or venation
• deciduous leaves
• more diverse and specialized leaves
• development of flowers and fruit

Question 2

angiosperms - lifespans (3):

Answer 2

annual - life cycle in one season
biennial - life cycle in two growing seasons
perennial - life cycle can span many growing seasons; flowers on new growth, while other plant parts persist

Question 3

evolution of flowering plants

Answer 3

• seeds (from ovules) enclosed in ovary (fruit at maturity) protect developing embryo
• strategies to spread quickly:
  – co-evolved w insect and animal pollinators
  – fruit helps seed dispersal at great distance
• flower is modified stem-bearing modified leaves
• sporophylls w microsporangia evolved into stamen (male), megasporangia into carpels (female)

Question 4

primitive flower

Answer 4

• many spirally arranged flower parts that are separate (not fused) and not differentiated into sepals and petals
• flattened and numerous stamens and carpels (complete/perfect)
• flowers radially symmetrical = regular
• superior ovary and long receptacle

Question 5

evolution of flowers: carpel

Answer 5

separate carpels of primitive flowers (SIMPLE PISTIL) fused together -> COMPOUND PISTIL w several carpels (think pepper)

Question 6

reproductive structures

Answer 6

• STAMENS attached around base of pistil; each stamen = a filament w another at top; pollen grains develop in anther
• PISTIL consists of stigma, style, ovary; fruit develops from ovary, contains ovule(s)

Question 7

perianth (not reproductive, for show)

Answer 7

COROLLA = petals - typically bright coloured to attract
CALYX = sepals - typically outermost and enclose other flower parts in bed
TEPALS - collective term used when petals and sepals are indistinguishable

Question 8

flower evolution: floral organization

Answer 8

• superior ovary (hypogynous flower): ovary on top of receptacle, other flower parts around ovary base
• inferior ovary (epigynous flower): receptacle or other flower parts fused to ovary and grew around it, other flower parts attached to top of ovary
• perigynous flowers: flower parts attached to corolla tube of fused petals, creating floral tube unattached to ovary

Question 9

flower evolution: floral structure

Answer 9

• complete flower: calyx, corolla, stamens, pistil
• incomplete flower: corolla or other parts missing (encourage cross-pollination)
• perfect flower - both stamens and pistil present
• imperfect flower - either stamens or pistil missing
• monoecious: male and female imperfect flowers on same plant
• dioecious: plant bears only male and others only female flowers

Question 10

major evolutionary trends (7)

Answer 10

• stamens & carpels become less leaf-like
• carpels fuse -> compound carpels (compound pistil)
• sepals & petals -> more dissimilar
• # floral parts -> fixed and reduced (from many to 5,4, or multiples of 3)
• floral parts progress from spiral arrangement to whorls
• # whorls decreases from 4 to 3, 2, 1
• radial symmetry gives way to bilateral symmetry

Question 11

trends of specialization in flowers

Answer 11

• flower parts fewer and definite in number
• spiral arrangements compressed to whorls
• bilaterally symmetrical flowers = irregular
• reduction and fusion of parts (incomplete or imperfect flowers)
• inferior ovary

Question 12

Flowers can be produced in singles or in _____ (group of flowers), and are also called _____

Answer 12

inflorescences
composite