Section PHACOCYSTIS
Section PHACOCYSTIS is represented by six species in Renfrew County. These are all wetland species notorious for confusion but in fact have diagnostic features that make their separation quite obvious.
Four of these species have upright pistillate spikes (Figure 1) and their bi-convex perigynia are quite distinct from each other (Figure 2). The inflorescences of these four species are also very different (Figure 3). Finally, for identification of immature specimens, Carex stricta has proximal sheaths that are strongly ladder fibrillose (Figure 4), Carex haydenii also has fibrillose sheaths but less clearly ladder fibrillose (Figure 4) while Carex aquatilis and Carex lenticularis do not exhibit fibrillose proximal sheaths.
The other two species, Carex crinita and Carex gynandra, are superficially identical to each other (Figure 5) and have pendulous pistillate spikes. Carex crinita and Carex gynandra also have perigynia and scales that are only marginally different (Figure 6) and the difference only becomes evident when compared side by side (Figure 7). Regardless, Carex crinita and Carex gynandra can be reliably separated by feeling the inner basal sheaths; Carex crinita has sheaths that are smooth and glossy while Carex gynandra has sheaths that are rough or scabrous (Figure 8). Using the back of your finger below your nail, slide your finger across the lower sheaths. If you feel resistance it is Carex gynandra, if it slides smoothly it is Carex crinita. Be careful because the tips of the lowest aphyllopodic basal sheaths are lance-like and will readily draw blood if you reach at the base of the plant without caution.
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Figure 1. Comparison of pistillate spikes (all to same scale). Of these four species, Carex haydenii is the only one without appressed perigynia. The perigynia of Carex lenticularis are often curved outward.
Figure 2. Comparison of perigynia (all to same scale). All perigynia are biconvex with both faces essentially identical. The face of Carex aquatilis perigynia are an inverted egg shape. Carex lenticularis has glaucous perigynia and several widely separated veins. The face of Carex haydenii perigynia are circular with a bronzy green coloration. The face of Carex stricta perigynia are oval shaped tapering gradually to form a beak.
Figure 3. Comparison of inflorescences (all to same scale). Carex aquatilis is easily recognized by the lowest bracts being conspicuously longer than the inflorescence. Tussocks of Carex stricta and Carex haydenii are very similar in size and habit but the inflorescence is much reduced for Carex haydenii. Carex lenticularis is least in stature among these four species.
Figure 4. Comparison of fibrillose proximal sheaths. Carex stricta is cleanly ladder fibrillose while the fibers of Carex haydenii do not form such an obvious ladder-like network. These features can be used to separate these two species out of season.
Figure 5. Natural habit of the superficially identical Carex crinita and Carex gynandra.
Figure 6. Comparison of perigynia to same scale. The sides of the Carex crinita perigynia taper more abruptly to the beak when compared to Carex gynandra. The perigynia of Carex crinita are also generally thicker than those of Carex gynandra (see Figure 7). Again, both of those features can only be discerned when both species are compared side by side.
Figure 7. Comparison of pistillate spikes.
Figure 8. Comparison of proximal sheath surface.