Poapalooza 2008
18 May 2008 - 18:30, Tinman said
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After a week of scorchingly clear days, Paopalooza 2008 resumed our regular wind&fog. The weather notwithstanding, about 15 grassophiles explored Mt D learning basic grass morphology, the distinction between native bunchgrasses and weedy introduced annual grasses, and the complexities of urban grassland ecology and management.
Here the troop separates weed grasses from native grasses under the watchful instruction of Major Tom:
And here we identify some small bunchgrasses that have survived a perilous location just off the main path:
This year most of the grasses had completed their flowering stage and many have finished dropping seed, so the findings were less than photogenic. However, the principles to be learned were just as useful as usual. A great time was had by all!
Update: Two superficially similar grasses — tufted hairgrass (Deschampsia cespitosa) and June grass (Koeleria macrantha) both have inflorescences with short spikes of packed spikelets. Deschampsia tends to have a more open spike with somewhat iridescent colors, but these features are subjective. The diagnostic distinction is in the spikelet features themselves.
D cespitosa has a quite distinctive spikelet in which the glumes are as long as the entire spikelet, there are two florets per spikelet, there are prominent hairs between the florets, and the lemma awns are prominent and originate low on the lemma:
K macrantha has longish glumes but shorter than D cespitosa, while there are no awns or hairs:
Although these shots are taken with a dissecting microscope back at the lab, these features are easily visible through a standard hand lens. Unless you’re packing your field DNA sequencer, don’t leave home without your hand lens!
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