Carex saximontana (Rocky Mountain Sedge)

Plant Info
Also known as:
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:part shade, shade; moist to dry; woods, thickets, prairies, wooded slopes
Fruiting season:May - June
Plant height:4 to 14 inches
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Spikes: Flower shape: indistinct Cluster type: spike

[photo of spike] A spike at the top of the stem with 2 or 3 staminate (male) flowers at the tip and pistillate (female) flowers below (androgynous), the staminate portion not more than 3.4 mm (1/8 inch) long. At the base of each pistillate flower is a leaf-like bract, the lowest one in the spike largest, to 5.5 mm wide and 3.5 cm (1.4 inch) long, wider and much longer than the spike and at least partially hiding it, the bracts becoming much smaller as they ascend the spike. One or 2 additional spikes on slender, erect stalks may arise from the base of the stem; these are androgynous or all-pistillate. The leaf-like bracts on these lateral spikes tend to be smaller and not as concealing as those on the terminal spike.

Leaves and stems: Leaf attachment: alternate Leaf attachment: basal Leaf type: simple

[photo of plant base] Two to 4 leaves are attached near the base, each up to 15 inches long, 2 to 5 mm wide, much longer than the flowering stems, hairless, mostly flat. Bases are wrapped in a yellowish to brown sheath that is not fibrous; some old sheaths may persist to the next season. Stems are slender, erect to ascending, 3-sided, varying in length but all under 12 inches tall at maturity (often half that) and remain much shorter than the leaves. Plants are clump-forming, not colony forming.

Fruit: Fruit type: seed without plume

[photo of maturing spikes] Fruit develops in late spring to early summer, the spike forming a cluster of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale; staminate scales may persist on the terminal spike. Each spike contains 2 to 6 fruits, erect to ascending and overlapping.

[photo of perigynia and achene] Pistillate scales are narrowly triangular to lance-shaped, tapering to a pointed tip, that of the lowest perigynia largest, green and leaf-like, the uppermost more scale-like, about as long as or shorter than the perigynia. Perigynia are 3.2 to 4.9 mm long, 1.6 to 2.5 mm wide, 2-veined, green when mature, urn-shaped in outline, round in cross-section, tightly wrapping the achene, abruptly tapered at the spongy base, abruptly tapered at the tip to toothless beak .6 to 1.2 mm long. Achenes are 2.5 to 3 mm long, nearly round in cross-section, rounded at the tip, abruptly tapered at the base, brown at maturity.

Notes:

Carex saximontana is an occasional sedge most often found on wooded bluffs and slopes.

Carex is a large genus, with over 600 species in North America and 150+ in Minnesota alone. They are grouped into sections, the species in each group having common traits. Carex saximontana is in the Phyllostachyae section; some of its common traits are: clump forming, basal sheaths brown and not fibrous, leaves V-shaped in cross-section when young, leaves hairless and much longer than fruiting stems, 1 to 5 spikes, terminal spike with staminate flowers at the tip (androgynous), lateral spikes stalked and androgynous or all-pistillate, lowest sometimes at or near the plant base, perigynia beaked and hairless, 2-veined or obscurely veined, beak toothless, lowest pistillate scales green and leaf-like, achenes 3-sided with 3 stigmas. The leaf-like pistillate scales are unique to species in this section.

Carex saximontana is one of the three members of the Phyllostachyae section in Minnesota and is distinguished from other Carex species by the combination of: clump-forming, largest leaves to 5.5 mm wide and much longer than the flowering/fruiting stems, stems of varying lengths and some spikes near the plant base, terminal spike with erect, leaf-like bracts wider than the perigynia that at least partially hide the terminal spike, perigynia to 4.9 mm long with a beak about 1 mm long. Most similar is Carex backii, which has perigynia 4.8 to 6.6 mm long with a longer, more gradually tapered beak. The third member of this section, Carex jamesii, has a much longer staminate portion on the terminal spike (to 14mm/½+ inch), periginia up to 7.5 mm long with a slender beak up to 3.8 mm long, and forms denser, leafier mounds in moister, rich forest habitats.

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More photos

Photos by K. Chayka taken in the garden. Photos by Peter M. Dziuk taken in Pope County.

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