Lecture 6: Plant Systematics II: Gymnosperms and Angiosperms

Question 1

Spores vs Seeds

Answer 1

Spores:
-Haploid: develop gametophytes
-Unicellular
-Minimal food reserves
-Minimal protection

Seeds:
-Diploid: develop sporophytes
-Multicellular embryo
-heterosporous (micro+mega)
-abundant food reserves
-Seed coat+protective

Question 2

Sporophytes of Ferns

Answer 2

Temporarily dependent on gametophyte (leaf+root grow from prothallus)
Evolutionary step: megagametophyte is retained inside the maternal sporophyte:
-plant releases spores which develop into the megagametophyte+sporophyte

-the megagametophyte is engulfed by the sporophyte and germination occurs inside

Question 3

Sporophytes of Ferns: megasporangium

Answer 3

sperm cells from the gametophyte are released
-surrounded by an integument (tissue layer)

Question 4

Sporophytes of Ferns: micropyle

Answer 4

opening in the integument that permits sperm cells to swim to the egg

Question 5

Progymnosperms

Answer 5

-extinct group of woody spore-bearing plants (ancestor)

-Vascular cambium: secondary xylem+phloem
-Cork cambium produces bark
-Xylem: composed of tracheas but no vessel elements
-No seeds

Question 6

Main divisions of gymnosperms: Cycadophyta (Cycads)

Answer 6

-Tropical and subtropical
-Leaves resemble palms/tree ferns
-Dioecious
-Motile sperm cells

Question 7

Main divisions of gymnosperms: Ginkophyta (Ginkgoes)

Answer 7

-Dioecious
-Deciduous: lose leaves in winter
-Unprotected ovules (no cones)
-Lacks vessels

Question 8

Main divisions of gymnosperms: Coniferophyta (Conifers)

Answer 8

FAMILIES:
1.) Pinaceae: needle-like leaves (pine, cedar, fir) suction cups
2.) Cupressaceae: scale-like leaves
3.) Taxaceae: flat leaves with feather-like arrangement

general:
-found in boreal forests
-evergreen
-Needles (leaf)+ resin (sap)
-Monoecious

(another main division of gymnosperms: Gnetophyta)