General: Perennial, tufted herb from short-creeping rhizomes; stems 30-70 cm tall, triangular, smooth, except slightly rough below the inflorescence, slightly longer than the leaves.
Leaves: Sheaths tight; ligules as long as wide; blades 4 to 8 per stem, borne on the lower 1/2 of the stem, 1.2-4.5 mm wide, folded or channeled, with silica papillae on the upper surface, cross-walled; lower leaves reduced, persistent.
Flowers: Spikes 3 to 6 (8), the terminal 1 or 2, sometimes 3 or 4, linear, 1.5-5 cm long, long-stalked, with many male flowers, the lower 2 to 4 spikes cylindrical, 3-6.5 cm long, with female flowers, short-stalked, the lowermost ones spreading; bracts subtending the lowest spike leaflike, sheathless, the lowest one longer than the inflorescence.
Fruits: Perigynia egg-shaped, 5-9 mm long, 1.7-3 mm wide, yellowish-green to reddish-brown, somewhat inflated, smooth, shiny, strongly nerved, rather abruptly contracted into beaks, the beaks 1.5-2 mm long, bidentate, with straight teeth; female scales lanceolate to egg-shaped, pointed, rarely awned, narrower and shorter than the perigynia, yellowish- to chestnut-brown, with lighter centres and narrow, translucent margins; stigmas 3; achenes 3-angled, 2.5-3 mm long.
Because Carex rostrata is rare (blue-listed) in British Columbia, it is important to be able to distinguish it from the common C. utriculata. With a few tips this can easily be done in the field and herbarium. The foliage of C. rostrata has a whitish-green to grayish blue-green appearance, and C. utriculata tends to be pale-green to green. These species often co-occur with C. rostrata preferring the wetter parts of a wetland and C. utriculata preferring the drier parts.
The whitish-green to grayish blue-green colour of C. rostrata seems to be caused by many tiny, tightly packed pimples (papillae) on the top (adaxial) side of the leaves. These papilla can only be seen with the aid of magnification strong enough (about 20-30X) to clearly see the tissue between the veins of the leaves (Fig. 2). The adaxial leaf surface of C. utriculata is usually smooth and green but may have some bumps (scabrous), however they do not affect the leaf morphology enough to alter the colour.
In the absence of magnification these two species can still be discerned based on macro-morphological leaf characters. The leaves of C. rostrata are narrow (rarely up to 4.5 mm wide), broadly U-shaped in cross section; the margins are rolled up back toward the centre of the adaxial surface (involute); and the bottom (abaxial) side lacks a thin, short ridge running down its centre. The leaves of C. utriculata are broad (>4.5 mm wise), broadly gull-winged to flat in cross section, do not have involute margins, and the abaxial surface has a thin short ridge running down its centre. The Flora of North America has a very nice plate (Ball & Reznicek 2002, p. 505) that illustrates the leaf cross-section profile of C. utriculata and the papilla of C. rostrata very well. However, this plate does not show the involute margins of C. rostrata (Ball & Reznicek 2002, p. 505).
Note Author: Chris Sears, Vegetation Biologist
Ecological Framework for Carex rostrata
The table below shows the species-specific information calculated from original data (BEC database) provided by the BC Ministry of Forests and Range. (Updated August, 2013)
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2020. E-Flora BC:
Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for
Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2020-12-04 7:14:55 AM
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