A few of the sea-side sedges belong to the genus Carex, in which the flowers are imperfect, and the fruit is enclosed in the outer parts of the flower. C. extensa thrives in salt marshes, growing to a height of a foot or more, and flowering about midsummer. Its fertile flowers form oblong erect spikelets, while the barren spikelets are solitary. The bracts are long and leafy, with short sheaths surrounding the stem. The leaves are curved in at the edges, and the fruit is oval and ribbed, with a short straight beak.
On sandy shores the Sea Sedge (C. arenaria) is often common, and its underground stems are used for sarsaparilla. It is a perennial species, growing to a height of about nine inches, and flowering in June and July. The flowers grow in an oblong interrupted spike, the upper spikelets being barren, and the intermediate ones barren at the tip. The fruit is oval, veined, and winged.
Another species of this genus—the Curved Sedge (C. incurva) —is sometimes to be seen on sandy shores, but it is rare, and is also a very small sedge, growing only to a height of about three inches. It derives its specific name from its curved stem, and may be further distinguished by its channelled leaves and the globular mass of spikelets which are barren on the top.
Fig. 282.—Male and Female Flowers of Carex, magnified
Some of the so-called rushes belong to the same order as the sedges, and a few of these are more or less restricted to the neighbourhood of the sea. The Salt-marsh Club Rush (Scirpus maritimus), as its name implies, is to be found in marshes near the sea. It is very variable in height, ranging from one to three feet, and displays its dense terminal cluster of spikelets in July and August. In this genus all the flowers are perfect, the glumes imbricated and bristled; and the present species may be distinguished by the glumes being divided into two sharply pointed lobes. A variety of S. lacustris may also be found on the sea shore, but it is somewhat rare. It has a leafless glaucous stem, and flowers arranged in compound spikes. The glumes are rough, and contain a compressed fruit.
A very small species of the Spike Rush (Eleocharis parvula), growing only one or two inches high, is sometimes found on the muddy shores of Ireland. It has perfect flowers, in a single terminal spikelet. The leaves are very narrow, growing from the base of the plant; and the round stem is enclosed in a single leafless sheath.
The true rushes belong to the order Juncaceæ. These have fibrous roots and narrow leaves, and bear clusters of brown flowers. The perianth consists of six parts, and the stamens are usually six in number. The ovary is generally three-celled, developing into a three-valved capsule. The Lesser Sea Rush (Juncus maritimus) is common in salt marshes, growing to a height of two or three feet, and flowering in July. It has a rigid leafless stem, bearing lateral clusters of flowers. The segments of the perianth are very narrow and sharp, and the seeds are enclosed in a loose testa. Closely allied to this species is the Great Sea Rush (J. acutus), which grows three or four feet high on sandy shores. In general characteristics it resembles J. maritimus, but the segments of the perianth are oval and have thin transparent margins; and it is a much rarer species.