Carex x subviridula Fernald (Section CERATOCYSTIS)
This is a sterile hybrid between Carex viridula and Carex flava and has been encountered a few times in Renfrew County where both parents are found. It seems to be a very robust plant forming large clumps (Figure 7). For the two examples I have found, both sexes occur on the spikelets; either having staminate spikes with a cluster of peryginia (Figures 2-5) or having androgynous pistillate spikes (Figures 6 and 7). The peryginia of the hybrid have morphology intermediate between the two parents and are always empty (Figure 1).
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Figure 1. Achenes, perigynia and scales of hybrid and parents.
Figure 2. Inflorescence.
Figure 3. Habit.
Figure 4. Inflorescence.
Figure 5. Inflorescence.
Figure 6. Inflorescence.
Figure 7. Habit.
Figure 8. Occurence map for Renfrew County and surrounding area.