JR's Botany Site

Eleocharis acicularis

Needle Spike-rush


Flowmead Country Park, Kent, May (Sue Buckingham)

Overview
➢ a very slight and slender plant with thread-like stems
➢ patch-forming
➢ often shy-flowering
➢ spikelets tiny, short, and few-flowered
➢ lowest glume encloses base of spikelet, and a quarter to a half as long as spikelet
➢ stigma 3-forked (as in multicaulis and parvula; contrast uniglumis and larger species, 2-forked)
➢ ripe nut has horizontal and vertical ridges, unique in the genus; style-base tiny
➢ grows in shallow water, or exposed, on silt/sand in +/- still water, often submerged, mainly lowland (contrast parvula: very local, estuary mud only)

Growth
➢ makes open or sometimes dense patches
➢ can make extensive submerged sheets in sheltered stretches of lowland rivers, but will only flower in dry seasons when exposed

Stems
➢ up to 15 cm but often much shorter
➢ only to 0.3 mm wide, narrower than the squatter plant parvula

Kent, May (specimens from Sue Buckingham)


Dorset, early September (photo Robin Walls; herb. specimen)


stem section


epidermal peel, showing two files of stomata


epidermal peel (closer); two stomata

Spikelets
➢ short, few-flowered
➢ lowest glume about quarter to half as long as the spikelet, and encloses its base
➢ glumes darker and richer brown than in parvula

Kent, May (Sue Buckingham)


Kent, May (specimen from Sue Buckingham)

Flowers
➢ stigma 3-forked
➢ perianth bristles often none, short if present

Nuts
➢ style-base (stylopodium) is tiny; not swollen
➢ style-base with tiny constriction

Habitat
➢ grows in shallow water, or exposed, on silt/sand in +/- still water, often submerged, mainly lowland (contrast parvula: very local, estuary mud only)

Spreading green carpets, Flowmead Country Park, Kent, May (Sue Buckingham)


With Pilularia, Hatchet Pond, Hampshire, August (Roger Smith)

Frequency & range
➢ scattered throughout. See ⇒distribution map.