Sunday, September 18, 2011

Ramets in Poa sierrae

Poa Section Madropoa is mostly restricted to high mountains of western North America: the exception is one species, Poa cuspidata of the ne U.S.  Of the 25 taxa total in the Section (FNA Vol. 24), most species are fairly widely distributed (except P. chambersii).  P. porsildii, an alpine calciphile, is the sole taxon, outside the limits of the western Cordillera (Rocky Mountains-Cascade-Sierra axis). 

Within the California Floristic Province, there are 8 endemic taxa of Poa Section Madropoa, a distinctive concentration. 

CAFP endemics
“Poa nervosa complex”
Poa rhizomata and Poa sierrae
Subsection Madropoa
Poa douglasii, Poa diaboli, Poa piperi and Poa atropurpurea
Subsection Epiles
Poa stebbinsii and Poa pringlei

Poa sierrae is odd in the clade: it is characterized by being rhizomatous, dioecious and by the distinctive scaly ‘bulbils’ produced on the rhizomes.  These ramets doubtless propagate by fragmentation, so it is puzzling why P. sierrae is quite narrowly distributed.  These ramets are nicely afforded 2x the page space in FNA Vol. 24 (p. 550) –fame!

This season, I visited “Lewisia rock” in the Feather River canyon, and collected P. sierrae at the type station.  On August 1st, the plants were still green but had flowered perhaps mid-June.  Collecting the material, I retained some rhizomes to cultivate.  Now, 6 weeks later after being potted and water, new growth is underway.

The top photo shows ramets field collected along a rhizome, in the fully dormant state.

The middle photo shows the larger ramet of the top photo after being potted where the base was set just at the soil surface, and after 6 weeks has not yet left dormancy: about 2 cm long

The lower photo shows two ramets: the left one is about 2 cm long and nicely expanding.  The smaller right-hand one is about 0.5 cm long and has just triggered.

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