Read Land-Plant Innovations
Read plant evolutionary trees as a sequence of innovations that made life on land possible.
Living-system questions are solved by matching a structure or organism to its function, process and stated condition.
Place innovations at the correct node
A trait at a node must be present in every branch above it and absent below it. Protected embryos distinguish land plants from their algal ancestors; stomata arise after the liverwort branch in this tree; tracheids appear only with club mosses and ferns. Follow the branches before matching trait names. Choose D.
Use bryophytes as clues to terrestrial adaptation
Bryophytes preserve early land-plant features. Stomata are associated first with the sporophyte/sporangial context and, in some bryophytes, extend to vegetative sporophyte tissue. Their walls also contain lignin-related phenolics that help protect against UV and microbes. These support statements A and C; do not generalise rhizoids or shoot form across every bryophyte lineage.
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- ✓A derived trait belongs at the earliest node shared by all descendants that possess it.
- ✓Protected embryos, stomata and tracheids mark successive land-plant innovations in the source tree.
- ✓Bryophyte phenolic wall compounds support protection during the transition to land.
Do not put a trait beside the organism most associated with it. In a tree, use the full set of descendants above each node.
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