(Cyperaceae) and the Rush Family (Juncaceae). The first of these families includes six commonly occurring genera (Carex, Scirpus, Cyperus, Eleocharis, Eriophorum and Dulichium), Carex and Scirpus being the most important as far as prevalence is concerned. The Juncaceae is constituted mainly of one genus, Juncus, of which there are several common species, and another rarely occurring genus, Luzula. The species of Carex, Scirpus and Juncus are numerous and are adapted to a variety of habitats, from very wet to dry and from exposed to shaded, in which they are invariably associated with each other and with the grasses.
The few diagnostic points presented in the following table will serve to separate these commonly occurring forms from the true grasses.
Differentiation of the grass-like plants of the families Cyperaceae and Juncaceae from the true grasses belonging to the Gramineae.
| Character | Gramineae | Cyperaceae | Juncaceae |
| Culm | Usually hollow; cylindrical or flattened.
|
Filled with pith, rarely hollow; generally three-sided. Nodes not conspicuous. |
Filled with chambered or open sponge-like pith; cylindrical. Nodes not conspicuous. |
| Leaf Arrangement. |
Two-ranked (Plate I. Figs, 1, 2, 4, 5). | Three-ranked (Plate 1, Fig. 6). | Three-ranked (Plate 1, Fig. 3). |
| Leaf Sheath | Usually split (Plate I. Figs. 2, 4), occasionally closed (Plate I Fig. 5). | Usually closed (Plate I, Fig. 6). | Open or closed. (Closed in Luzula). |
| Auricles | Present or absent | Absent. | Absent or present as rounded extensions of the sheath margins |
| Collar | A distinct band. | Indistinct. | Indistinct. |
| Ligule | Present, rarely absent. | Absent, or weakly developed. | Absent, or weakly developed. |
| Leaf Blade | Usually flat, some times closely folded involute or
bristle-like; glabrous or pubescent.
|
Flat, plicate (Plate II. Fig. 1) or bristle-like: rarely
pubescent.
Margins usually scabrous. |
Channeled (Plate II, Fig. 2) or terete (flat in Luzula); glabrous
(hairy on margin and at mouth of sheath in Luzula). Margins smooth on flat or channeled blades. |
4. CHARACTERS USED IN THE IDENTIFICATION OF GRAMINEAE
The points of separation used in the included key are based on the characters of the bud-shoot and leaves on the vegetative or lower parts of the flowering shoots of the plant. The leaves high on the flowering culm
