This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
The habitat of the plant is muddy salt marshes. The habit is tufted. The stems are thickened below. The leaves are radical, linear, fleshy, flattened at the tip. The scape is curved. The flowers are in a loose, simple, long raceme, and are greenish. The fruit is egg-shaped, oblong, not appressed to the scape. There are 6 stamens. The 6 carpels are grooved at the back. The plant is 10-12 in. high, flowering between May and September, and is a herbaceous perennial.
The habitat of this species is salt water and brackish ditches, salt-marshes. The plant has the pondweed habit. The stem is slender, much-branched. The leaves are linear, narrow, opposite or alternate, the first leaf of each axillary shoot opposite a narrow, blunt, or notched cellular scale, arising from the base at the side next the axis. The flowers are in a spadix arising from the leaf-sheath. The leaf-sheaths are inflated. The flower-stalk is spirally coiled (as in Vallisnerid), long, short and straight in flower, when fruiting 5-6 in. The anther-cells are \\ times as long as broad. The nut is egg-shaped, green, beaked, obliquely erect, the stalk 1-2 in. The plant is floating. It flowers between July and September, and is a herbaceous perennial.
The habitat of this plant is salt marshes. The plant has been regarded as merely a subspecies of the last. The plant as a whole is very slender. The leaves are narrower, slender to linear. The sheaths are smooth, close, closely pressed to the stem. The fruiting-stalks are short, wavy, not spiral. The anther-cells are more or less round, rather square, as broad as long. The drupe is swollen below, obliquely ascending when young, the beak long (hence rostellata). The plant is floating. The flowering period is between June and August. The plant is a herbaceous perennial.
Zannichellia pedunculata, Reichb. = Z. maritima, Nolte. - The habitat of this plant is brackish water. The habit is that of a pondweed. The leaves are opposite, threadlike. The achenes are 2-5, stalked (hence pedunculata), with strong prickles on the back. The style is as long as the achenes. The stigma is large, scalloped. The anther-stalks are up to 1/4 in. long. The anthers are 2-celled. The plant is floating. Flowers are to be found between May and August. The plant is a herbaceous annual.
The habitat of this plant is muddy estuaries or salt water. The habit is ribbon-like or zosteroid (hence Zostera), like other grasswracks. The plant is small (hence nana). The leaves are slender, linear, 1-3-veined. The flower-stalks are slender, pale in colour, half as broad and as long as the spathe. The spathe is swollen above the stalk, oblong to lance-shaped, with a short blade. The spadix is few-flowered, short, with 2-5 clasping bands, the margin having membranous appendages bent inwards. The nuts are smooth, faintly furrowed, the seeds shining black when ripe. The plant is floating, flowering between April and August, and is a herbaceous perennial.