Eleocharis robbinsii Oakes, Robbins' spikerush
Eleocharis robbinsii is sparse in Renfrew County growing in shallow water of lakes, ponds and slow moving rivers. Its distribution seems to be restricted to the northwestern portion of the county. This species is unique amongst the Eleocharis of Renfrew County in exhibiting dimorphic stems; flowering stems that are stiff and conspicuous above the water surface (upper part of Figure 1 and Figure 2) and threadlike vegetative stems that are flaccid (lower part of Figure 1). Colonies are quite dense but the flowering stems are heavily grazed by Canada Geese making it difficult to find complete specimens.
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Figure 1. Inflorescence, achenes, scales, basal sheaths and vegetative stems. The parts shown above the ruler are those exposed above the surface of the water. The middle spike is a non-flowering culm, not a leaf. The parts shown below the ruler are the submerged bases of the culms, surrounded by the threadlike vegetative stems.
Figure 2. Habit in nature.
Figure 3. Habit in nature.
Figure 4. Occurence map for Renfrew County and surrounding area.
| Accession # | Collector | Date |
|---|---|---|
| CAN 568567 | D.F. Brunton | 1989-August-16 |
| CAN 570174 | T.C. Brayshaw | 1963-October-20 |
| DAO 251771 | T.C. Brayshaw | 1963-October-10 |
| CAN 570175 | T.C. Brayshaw | 1963-October-04 |