Flowers of northwestern blue-eyed grasses are protandrous (meaning that the male parts of the flower mature before the female parts). This promotes outcrossing and reduces chances of self-pollination in self-compatible plants. Solitary bees (family Megachilidae) facilitate pollination (Henderson 1976). Bumblebees (Bombus spp.) have also been observed visiting the flowers. Flowers do not open until late morning or mid-day (Gamon 1991). Flowering largely depends upon elevation and weather patterns during late spring and early summer. Lower elevations (ca 2000 ft or 600 m) begin flowering in early June and have mature capsules by mid July, while those at higher elevations (3700-4000 ft (1100-1220 m)) begin to flower in mid to late July and have mature capsules around mid-August (Gamon 1991). Sisyrinchium idahoense occurs in a similar habitat (Gamon, 1991) and is found growing along with S. sarmentosum in at least one large site (Karst, pers. comm.). This species is clonal (Gamon 1991) and when heavily grazed, this may be the primary means that the plant reproduces itself. Sisyrinchium sarmentosum's associated species include Deschampsia cespitosa, Alopecurus pratensis, Phleum pretense, Poa palustris, Juncus tenuis Juncus ensifolius, Carex vesicaria, Carex microptera, Agrostis idahoensis, Fragaria virginiana var. platypetala, Prunella vulgaris, Trifolium repens, Potentilla drummondii, Ranunculus flammula, Solidago canadensis, Veronica scutellata, Botrychium multifidum, Antennaria microphylla and Viola adunca (Gamon 1991). Common associated shrubs and trees include Spirea douglasii, Pinus contorta, Picea engelmannii, Acer circinatum and Populus trichocarpa (Gamon 1991).