Section GLAREOSAE
There are six species from this section found in Renfrew County. All of these species are primarily found in wetlands. They are characterized by their lens shaped, short beaked perigynia (Figure 1) and gynecandrous spikelets (Figure 2 and 3). Carex trisperma and Carex billingsii are closely similar and C. billingsii was once considered a variety of C. trisperma [Kirschbaum, 2007]. C. billingsii has fewer perigynia in the spikelets (Figure 3) and finer involute leaves (Figure 4) compared to C. trisperma.
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Figure 1. Perigynia of Section Glareosae. Left member of each pair is the abaxial face, right member of each pair is the adaxial face. All perigynia to same scale.
Figure 2. Comparison of Carex canescens, Carex brunnescens and Carex arcta inflorescences. All to same scale.
Figure 3. Comparison of Carex billingsii and Carex trisperma inflorescences.
Figure 4. Comparison of Carex billingsii and Carex trisperma leaves.
References
Kirschbaum, C.D., The Taxonomy of Carex trisperma (Cyperaceae), J. Bot. Res. Inst. Texas 1(1): 389–405, 2007