Flowering Plant Families, UH Botany

Commelinidae: Cyperales. The Cyperaceae are grasslike, herbaceous plants comprising about 70 genera and 4,000 species, commonly found in wet or saturated conditions. The stems are usually 3-angled and solid. The leaves are alternate, commonly in 3 ranks, usually with a closed sheathing base and a parallel-veined, strap-shaped blade. The flowers are very minute and are bisexual or unisexual. Each floret is in the axil of a chaffy bract and these are arranged spirally or distichously in spikelets. Perianth may be represented by scales or bristles in two whorls or may be entirely lacking. The androecium consists usually of 3 distinct stamens but 1, 2 or rarely 6 may be present. The gynoecium consists of a single compound pistil of usually 2 or 3 carpels, a single style usually with 2 or 3 lobes or branches, and a superior ovary with a single locule containing a single basal ovule. Sometimes the ovary is enveloped by a membranous sac called a perigynium. The fruit is a 3-angled or lens-shaped achene.

Carex sp., sedge. Note the grasslike leaves. This genus has unisexual flowers. Staminate flowers are found in the axils of purplish bracts in the upper spikelets and pistillate flowers occur in the lower spikelets. Each pistil has a 3-branched style.

Carex wahuensis, sedge. Hawaiian endemic.

Cyperus rotundus, nut grass, note 3-ranked leaves, triangular culm, flattened spikelets with exserted styles.

Lepironia articulata. Note the stamens exserted from the bracts of the spikelets.

Bulbostylis capillaris. This sedge is commonly only about 6-9 cm tall and has very small brownish spikelets.

Cyperus papyrus, papyrus. This is a very large sedge that was cultivated by ancient Egyptians for a variety of uses, including paper.

Uncinia uncinata. This unusual native Hawaiian sedge has a hooked rachilla that aids in the dispersal of the fruits by birds. The photo shows one of the fruits attached to fibers of a wool sweater that was worn into the plant's rainforest habitat.