BIOL 111 Lecture 16: Trees and Seeds

• School: McGill University
• Department: Biology
• Course: BIOL 111
• Professor: Andrew Hendry

Document Summary

Shade out competitors: better wind dispersal of spores and seeds. The rise of trees: definition: plant with single stem and branching canopy that can reach large heights via specialized cells (it got some sort of adaptations that allowed it to overcome gravity to grow tall) Strict definition: has wood and increase in girth. Exclude early tree-like plants: wood, vascular cambium: modern trees have ring of dividing (growing) cells beneath the bark (produces new/lignified xylem ---- water and nutrients go up and phloem ----- sugars flow down) b. What is wood: wood is made of the dead secondary xylem/phloem (strong enough to get hardness) c. the reason of seeing tree rings: most produce in the temperate climates, and growth stops growing in the winter. No leaves, just increasingly fine branches ---- photosynthesis using stem tips. Branched trunks 30m with reinforced branch joints: wood similar to conifer wood. Reproduced via spores ("free-spore": link between ferns and gymnosperms.