Thursday, April 23, 2020

Bulbils on the Spikelets of Poa bulbosa

I was walking on the sidewalk leading to my gym, when I noticed some tiny but interesting panicles on grasses by the side. The spikelets seemed to have green twisting protrusions coming out from them, so I took some samples home with me.

Once I got home I took some macro shots of the spikelets, and posted it to the midwest graminoid facebook group, where some helpful members immediately identified the samples as Poa bulbosa. The ID was confirmed by the Grass Identification group as well.

P. bulbosa is a perennial bunchgrass that originated from the Mediterranean region and was introduced to the USA in the early 20th century. It is a successful invasive species, and can be found in a variety of disturbed areas such as roadsides and pastures.

Although the species reproduces sexually in its native areas, it reproduces mainly by asexual means in its introduced range. This is accomplished by either the use of of above-ground bulbs along its base that split off from the parent plant, or by the clonal propagation of bulbils that rise from its spikelets. Such bulbils are transformed florets that produce new plants when separated from the parent.

I've always thought that grasses have some of the most beautiful reproductive structures in plants, although this might be surprising to those who rarely glance at the inflorescence of members of this family, but instead wax lyrical about a rose, or an orchid flower.

The notion that grass spikelets could harbor more than just the usual true florets was amazing to me, so I would like to share some of the images here with you.


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