The genus Eleocharis (UK species)


To download a simple (over-simple?)
Field-key to the seven Eleocharis species, click here. [PDF 652 KB]

Rhizomatous perennial sedges, emergent from shallow or deeper water, or of damp soils.

Growth-forms vary between strongly tufted (e.g., multicaulis), loosely tufted (e.g., quinqueflora), and patch-forming (e.g., austriaca); sometimes making very extensive sheets (e.g., palustris).

Stems circular or somewhat flattened in section, ascending and typically +/- vertical, terminated by a single spikelet (for which “spike” might be a preferable term).


stem sections, (left) austriaca; (right) multicaulis


There are
no ‘leafy shoots’: leaves are reduced to leaf-sheaths on stems; leaf-blades are absent (contrasting with Trichophorum, where there is a short leaf-blade).


transversely-truncate uppermost sheaths in uniglumis


Note that spikelets may – and often do – abort at an early stage of stem-growth, leaving a sterile ‘bare-topped’ stem which may be taken for a ‘leaf’ (and indeed substitutes for one).


The inflorescence is a terminal spike (or spikelet) consisting of a number of flowers arranged spirally along an elongated receptacle, each protected behind a single non-enclosing chaffy glume (or scale).

There is no elongated basal bract to the spikelet (such as in
Carex), the bract(s) being reduced to one, or two, glume-like structures (more rigid than the typical glumes above) one of which itself may in some species shelter a flower.


many-flowered spikelets, upper flowers still with ripe anthers, of palustris


much smaller and fewer-flowered spikelet of quinqueflora

Flowers are bisexual, with three stamens (the filaments of which are long-persistent), and a stigma forked into either two or three from a longish style.

The stigma/style is usually shed at some point leaving the
style-base or stylopodium, important in identification.

The
perianth is reduced to a few (0-6) bristles at the base of the ovary, which do not elongate after flowering (unlike in the cottongrasses – Eriophorum – in which the bristles make the familiar head of ‘cotton’ in fruiting).

These bristles arise from a narrow collar at the base of the nut, and have numerous minute rear-pointing hooks, which distinguish bristles from the persistent filaments (see pictures below).

The
fruit is a bare nut, topped by the persistent style-base (stylopodium) which in some species is confluent with the nut (e.g., quinqueflora, upper), and in others is enlarged with a distinct ‘neck’ above its junction with the nut (e.g., palustris, lower).


nuts:
above,
quinqueflora: confluent style-base (style retained in this pic), whitish filaments, brown bristle

below,
palustris: 'necked' style-base (style missing in this pic), 3 long and broad filaments, 4 bristles with minute hooks





Links to the other Eleocharis spike-rush pages (also accessible from the sidebar)