Gymnosperms

What are the two non-confier gymnosperm groups?

Cycadophyta (Cycads) and Ginkgophyta (Ginkgos)

Cycads two familes? 

Cycadaceae and Zamiaceae

Cycads only U.S. species?

Zamia integrifolia

Cycads are a __________ group.

Cycads are a monophyletic group.

Cycads are _____-like or ______-like in appearance.

Cycads are palm-like or fern-like in appearance.

Cycads have _____ stems, with leaves at the ______ of ________ trunks.

Cycads have woody stems, with leaves at the apex of unbranched trunks.

Cycad leaves are __________-__________ with __________ leaf bases. Leaflets have partial ________ vernation.

Cycad leaves are pinnately-compound with persistent leaf bases. Leaflets have partial circinate vernation.

Two types of Cycad roots?

1. coralloid and upwardly growing roots

2. contractile roots

Only gymnosperm known to have a symbiotic relationship with a nitrogen fixing organism.

Cycads

Cycad Reproductive Traits

• dioecious

• seeds borne on megasporophylls 

• seed cones are the largest ever

• seeds are large and bright colored

• pollen-bearing cones can be numerous, up to 100, and are generally morphologically dissimilar from seed cones

• 100s of microsporangia on underside of microsporophyll

• pollinated by insects

• sperm are motile

Most cycads can reach reproductive maturity within __ year in cultivation.

15 years

Cycads conservation status

disappearing due to over-collecting and habitat destruction

one extant species of Ginkgo

Ginkgo biloba

________ date back to the Jurassic

Ginkgo

What group is conifer-like in overall growth form (excurrent branching)?

Ginkgo

Ginkgo leaves are highly unusual why?

fan-shaped, with forked venation, and decidious

Ginkgo have _____-shoot morphology

short-shoot morphology

Are ginkgo closer to cycads or conifers? Why?

Cycads

• dioecious

• huge, motile sperm

• unflattened, fleshy seeds

second-most dominant seed plant today

conifers

~700 species

Characteristics of Conifers

• simple, single-veined leaves

• mostly evergreen

• excurrent branching

• wind pollinated

• seeds and pollen in separate cones

  • seed cones - compound

  • pollen cones - simple

• worldwide distribution except Antarctica and the lowland tropics

conifer means “cone-bearer” even though…

some members lack seed cones (Taxaceae)

sister to all other conifer families

Pinaceae

Pinaceae innovation

seed has long terminal wing and the ovule is inverted

Podocarpaceae and Araucariaceae are ________ to one another, constituting a mostly _________ hemisphere clade

sister

southern

Podocarpaceae and Araucariaceae innovation

only one ovule per seed-cone scale

Early ideas about Taxaceae (without seed cones) not being conifers are incorrect. Why?

Taxaceae have lost seed cones

Taxodiaceae innovation

fusion of seed-cone scale with subtending bract

Gnetales three families

Ephedraceae

Gnetaceae

Welwitschiaceae

Ephedraceae general info

• 35-45 species

• semi-arid habitats

• scale-like leaves

• photosynthetic ridged stems

Gnetaceae general info

• ~30 species of vines, 1 tree

• tropical rainforests

Welwitschiaceae

Welwitschia mirabilis - only species

• Darwin’s “platypus of the plant world”

• found in the Namib Desert of SW Africa

• one pair of foliage leaves grow throughout life

• branched strobiliferous shoots

Morphological characteristics of Gnetophytes

• opposite decussate, or whorled leaves

• protruding tubular inner integument of ovules (two integuments)

• both pollen and seed cones are compound

• football-shaped, striated pollen