Luzula

Herbs, perennial, usually cespitose, often with short, mostly vertical to running rhizomes and/or (less commonly) stolons. Culms round. Cataphylls absent. Leaves: sheaths closed, without auricles at throat (junction with blade), usually pilose; blade flat or channeled, never septate, margins with long, soft, multicellular hairs, apex often thickened (callous), veins commonly indistinct. Inflorescences terminal; flowers inserted individually or in dense clusters (glomerules) variously arranged; bracts subtending inflorescence (proximal inflorescence bracts) 2, mostly leaflike; bracts subtending inflorescence branches 1–2, reduced; bracteoles subtending flowers 2–3. Flowers: tepals 6, in 2 whorls; stamens 6. Capsules 1-locular, generally globose; beak often formed by persistent style base. Seeds 3, globose to ovoid, base often with tuft of fibrous hairs (vestige of funiculus); nutritive appendage from outer seed coat (caruncle) often present, white, barely visible to ± equaling seed body. x = 6.

Distribution

Temperate and arctic regions worldwide, tropical mountains.

Discussion

The leaves of Luzula are primarily basal; cauline leaves are usually reduced.

Luzula species have diffuse centromeres and small chromosomes. That has resulted in much confusion in interpretation and reporting of chromosome counts. No attempt has been made to include reported counts that could not reasonably be verified by the author.

Excluded species: Luzula sudetica (Willdenow) de Candolle. Although reports of this European species appear frequently in the North American literature, I have seen no specimens that confirm its presence. No chromosome counts are published for North American material. Since this species has a distinct cytotype, 2n = 48 (H. Nordenskiöld 1956), it should not be difficult to verify on this basis.

Species ca. 108 (23 in the flora).

Selected References

None.

Lower Taxa

Luzula subg. Anthelaea, Luzula subg. Luzula, Luzula subg. Pterodes

Key

1	Flowers in dense clusters (glomerules); inflorescences spikelike or umbellate; seeds with caruncle conspicuous to barely visible	Luzula subg. Luzula
1	Flowers solitary or in small clusters of 2–4; inflorescences mostly unbranched or dichasial; seeds with caruncle conspicuous to absent.	> 2
2	Flowers solitary; inflorescences corymbose, rarely branching; seeds with caruncle conspicuous	Luzula subg. Pterodes
2	Flowers mostly in pairs, rarely in clusters of 3–4, or solitary; inflorescences paniculate or dichasial; seeds with caruncle inconspicuous or absent	Luzula subg. Anthelaea