Montana Field Guide

PLANTS: Rhizomatous, perennial herbs with erect stems reaching 7-90 cm tall. Plants may be tufted or solitary. Source: Lesica et al. 2012.

LEAVES: Leaves are bladeless and reduced to 2 sheaths on the lower stem. The sheath of the distal leaf is firm and persistent. The leaf tip is obtuse to acute without a tooth-like projection. Source: Lesica et al. 2012.

INFLORESCENCE: A 5-25 mm long single spikelet with numerous flowers. Florets are tightly packed and spirally arranged. Source: Lesica et al. 2012.

The specific epithet palustris translates from Latin to “marshy” or “marsh-loving” referring to this species’ preferred habitat Eleocharis is made up of the two Greek words hele- and -charis meaning “marsh” and “grace” respectively (Merriam-Webster).

This species flowers May through September and fruit develop during late summer. Source: Flora of North America 2019.

Montana has eight Eleocharis species. They are generally mat-forming wetland herbs with inflorescences consisting of a single, solitary spikelet (Lesica et al. 2012).

Creeping Spikerush - Eleocharis palustris
*Habit: An erect, rhizomatous perennial.
*Stems: More or less cylindrical stems that are 7-90 cm tall with purple bases.
*Spikelets: 5-25 mm long with numerous flowers.
*Achenes: A yellow to brown, smooth, obovate achene that is 2-3 mm long. The upper portion of the achene is pyramidal in shape and appearing separated from the lower portion which is orbicular to lenticular in shape.
*Stigmas: 2

Beaked Spikerush - Eleocharis rostellata
*Habit: A low-growing, tufted (cespitose) perennial. Stems are erect or arching and rooting at the tips.
*Stems: More or less flat, some arching to the ground and rooting at the tips. Plants are 10-80 cm tall.
*Spikelets: 4-10 mm long with few to many flowers.
*Achenes: Grayish-green, about 2 mm long. The upper portion of the achene is conical and confluent with the lower portion that is 3-sided to nearly round in cross section.
*Stigmas: 3

Few-flower Spikerush - Eleocharis quinqueflora
*Habit: An erect, short-rhizomatous perennial.
*Stems: 5-25 cm tall and tufted.
*Spikelets: 4-8 mm long and usually with 5 flowers.
*Achenes: Brown, smooth, narrowly obovate, and 2-3 mm long. The upper portion of the achene forms a distinct beak that is confluent with the lower portion that is 3-sided.
*Stigmas: 3

Creeping Spikerush prefers vernally wet to shallow water of wet meadows, margins of lakes, ponds, marshes, and fens from plains and valleys to montane zones (Lesica et al. 2012).

POLLINATION
Creeping Spikerush is a wind-pollinated species (Hauser 2006).

ADAPTATIONS
Creeping Spikerush tolerates pioneer conditions and thrives in disturbed sites (Hauser 2006). It can be found establishing in early-, mid-, and late-successional wetland sites (Hauser 2006). It can quickly populate mud flats after water draws down, yet it can grow in areas flooded up to 1 meter deep and withstand inundation for up to 4 months (USDA 2005). The root masses of Creeping Spikerush extend as deep as 40 cm into the soil profile and can withstand water table levels as low as 30 cm below the surface (USDA 2005).

FIRE
Creeping Spikerush is somewhat adapted to fire disturbance and populations may increase and rebound quite quickly after fire. Dormant seeds and rhizomes are fire tolerant and can re-establish after burning by means of these below-ground features (Hauser 2006). However, all above-ground plant matter is top-killed by fire (Hauser 2006). Studies of sedge meadows in both Oregon and Wisconsin showed that Creeping Spikerush populations increased significantly over the first two years after fire, but then returned to normal population sizes (Hauser 2006; Kost et al. 2000).

WILDLIFE USE
Due to its high vegetative protein content and digestibility, Creeping Spikerush is an important early season food source (USDA 2005). The seeds are heavily grazed late in the season by livestock, large game animals, and ducks (USDA 2005). This species also provides nesting cover for various waterfowl (USDA 2005).

Creeping Spikerush has medium seed abundance, moderate seed spread rate, medium seed vigor, and moderate vegetative spread rate (USDA, NRCS 2019).

FLOWERS [Lesica et al. 2012]
Flowers consist of 4 to 6 perianth bristles, 2 stigmas, and 3 stamens. Perianth bristles are longer than the achene. The scales, found at the base of each flower, are 2.5-4 mm long, and brown to purple with a green or tan midrib. The lowest 1 or 2 scales are empty, lacking flowers or achenes.

ACHENES [Lesica et al. 2012]
Achenes are yellow to brown, smooth, obovate, and lenticular. They are 2-3 mm long including the short-stemmed, triangular tubercle that is 0.5 to 1 mm long. The upper portion of the achene is pyramidal in shape and appearing separated from the lower portion which is orbicular to lenticular in shape.

VEGETATIVE [Hauser 2006]
Creeping Spikerush is a clonal species that reproduces asexually by rhizomes. This allows it to form homogenous, monotypic stand anywhere from 1 to 6 feet in diameter. Rhizomes form a near linear growth path with almost no branching. This may aid in efficiently escaping overcrowded areas with already dense vegetation.

LIFE CYCLE [Hauser 2019]
Creeping Spikerush is a perennial species. Fruit does not develop until an individual is 2 to 3 years old. Seeds usually germinate from mid spring through early summer and ripen from July to August. At maturity, the inflorescence quickly disarticulates to spread its seeds by the wind. Seeds that do not germinate are stored in the seed bank. In aquatic habitats, the rhizomes of Creeping Spikerush develop rapidly during mid to late summer.

RESTORATION USES
Creeping Spikerush is a particularly useful species for restoration projects due to its thick, mat-forming rhizomes that aid in controlling erosion and compaction (USDA 2006). Its beneficial effects on soil stability allow sensitive plant species to return and assist in restoring an area to original healthy wetland conditions. When planted in natural areas, this species provides food for wildlife and hosts many beneficial bacteria that help filter waste out of groundwater.

Russian Olive Elaeagnus angustifolia) invasions have detrimental effects on Creeping Spikerush populations (Hauser 2006). Wetland sites that are infested with Russian Olive have significantly lower frequency of Creeping Spikerush than uninfested sites (Carman et al. 1982).