Included in this key are only those species found in the area surveyed at Buttermilk Falls State Park.

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Vascular Plants of the Gorge at
Buttermilk Falls State Park (Ithaca, NY)

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Continue to the Graminoid key now.

Basic Distinctions Between the Graminoids

     Grasses tend to have stems that are round in cross-section. Sedges tend to have stems that are angular or triangular in cross-section (i.e., having lengthwise ridges). Rushes have stems that are either round or flattened in cross-section, but never with lengthwise ridges.

     None of these species produce leaves that are borne on a "leaf-stalk", as would be the case with a tree or shrub. Instead, the base of the leaf continues as a sheath that mostly surrounds the stem. Grasses tend to produce leaf sheaths that may be split partially or entirely down the middle, lengthwise. These are called "open sheaths". Sedges tend to produce leaf sheaths that do not split down the middle. Those are called "closed sheaths". Juncus species have open sheaths. Wood-rush species have closed sheaths.*

     In general, graminoids have both female (pistillate) and male (staminate) reproductive organs, often enclosed partly or entirely within scales, though in some sedge species female and male parts are located separately within the inflorescence. For rush species, female and male organs are located together, and flowers are not concealed by scales.

The fruits of grasses are dry, one-seeded grains (caryopsis), in which the seed coat is fused to the persistent two scales that enclose the floret. The fruits of sedges are dry individual nutlets (achenes), each of which is enclosed in a scale-like bract (perigynium), but not fused to it. The fruits of rushes are three-parted capsules that split open at maturity, releasing many seeds. 

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