LOLOL

Pollen can adapt to specific vectors

• Sticky pollen → insects

• Light, powdery pollen → wind

Sticky pollen

→ insects

Light, powdery pollen

→ wind

Angiosperms can time flowering to..

match pollinator activity, increasing efficiency

Rapid life cycles in angiosperms allow..

multiple generations per year, unlike slow gymnosperm cones.

Mechanical (auto-) dispersal

ejection or bursting pods (e.g., touch-me-not).

Animal-mediated dispersal

 seeds eaten and excreted, or stick to fur.

Water dispersal

buoyant seeds like coconuts

Mimicry

some seeds mimic food or insect eggs to attract carriers.

Gymnosperms (conifers) stabilize soil and form

boreal forests

angiosperms dominate..

diverse biomes.

Angiosperm radiation (~140 million years ago) driven by

coevolution with insects

Seed plants helped ecosystems transition from..

simple spore plants to complex forests.

Gnetophytes

only gymnosperms with vessel elements → faster water transport.

Ginkgo

“living fossil,” survived mass extinctions unchanged

Secondary metabolites beyond alkaloids:

• Phenolics → reduce digestibility

• Terpenes → repel herbivores or attract predators of herbivores

Phenolics

→ reduce digestibility

Terpenes

→ repel herbivores or attract predators of herbivores

Physical dormancy

hard seed coats prevent germination until environmental cues are favorable.

Human Uses Beyond Food

• Fibers: cotton, hemp, linen

• Timber: construction, furniture, paper

• Biofuels: corn ethanol, palm oil

• Pharmaceuticals: paclitaxel (yew), aspirin (willow)

• Aesthetic & ecological uses: landscaping, reforestation, erosion control

Pharmaceuticals

paclitaxel (yew), aspirin (willow)

Flowers and pollinators evolve together →

increased plant and insect diversity

Herbivores adapt to plant defenses

evolutionary “arms race.”

Seed dispersal and pollination adaptations promote

genetic diversity and ecosystem stability.