Tuesday, September 30, 2014

Cyperus odoratus

I recently published a post discussing the differences between two commonly confused species in the genus Cyperus, C. esculentus and C. strigosus.  In that post, I mentioned a third species that can be confused with these, C. odoratus.  After seeing C. odoratus today, I thought it would be useful to include some photos of this species for comparison with the previous two.

Cyperus odoratus inflorescence
The spikelets of C. odoratus are similar in color to those of C. esculentus, often having an orangeish hue, turning brown upon maturation.  The spikelets are often more dense in the inflorescence than in C. esculentus, but not as densely packed as those in C. strigosus.

Three Cyperus odoratus spikelets
As in C. esculentus and C. strigosus, the spikelets of C. odoratus consist of several flowers, each of which is subtended by a scale.  Each scale is similar in length to those of C. esculentus, ranging from approximately 2-3 mm (the scales of C. strigosus are 3-4 mm long).

The spikelets of Cyperus odoratus disarticulate below the scales of individual flowers (Steve Sass hand model)
One of the main morphological differences between C. odoratus and C. esculentus is that, when mature, the spikelets of the former disarticulate below each scale, whereas those of the latter disarticulate at the base of the lowest flower only.  To see this, pull on the end of the spikelet and see if it breaks off somewhere along the spikelet (C. odoratus) or if the entire spikelet breaks off as a unit (C. esculentus).  Be sure to try this with numerous spikelets, not just one.

Base of Cyperus odoratus
Yet another way to distinguish between C. odoratus and C. esculentus is to look at the base of the plant.  In the former, there aren't many leaves coming from the base of the plant, whereas the leaves in the latter are heavily basally disposed.  In addition, C. odoratus does not produce the tubers often produced by C. esculentus.


Tim Jones said...

Like the parenthetical Steve Sass hand model. Nice work on this Scott.

Scott Namestnik said...

Thanks Tim.