Racomitrium heterostichum (Hedw.) Brid.
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Synonym: Bucklandiella heterosticha (Hedw.) Beknarek-Ochyra & Ochyra
Special status: NONE
Recognition: Smallish for a racomitrium, this species is recognized in the field by its long, white hairpoints and shoots which are dark, blackish green at the base and relatively pale, yellowish olive green at the tip. It is easily confused with Grimmia trichophylla and relatives. Fortunately, Racomitrium heterostichum usually is fertile and the left handed twist of its seta will distinguish it from the similar species of Grimmia. If a strong field gestalt has not been learned, it is necessary to prepare leaf sections to confirm identification. It has unistratose margins, and from the other species of Racomitrium with unistratose margins it is distinguished by the flat costa, only two cells thick at midleaf and most of the way to the base of the leaf. Sections of costa near the leaf base may be up to 12 adxial cells wide, yet still be mostly 2 cells thick.
Distribution: Common and widespread, this is one of the most frequently encountered species on dry rocks. It rivals Racomitrium varium in abundance but does not grow so much in the riparian zone as that species. Jackson County: Wagner 9991a (OSC); Klamath County: Wagner 8489 (OSC); Lane County: Wagner m1466 (OSC).
Comments: Many of the species of Racomitrium which are now recognized were treated as varieties of Racomitrium heterostichum (as Rhacomitrium heterostichum) by Elva Lawton. Most of the modern species concepts were first clearly enumerated by Frisvoll (1988) and subsequently reinforced by Bednarek-Ochyra (1995) and Ochyra and Bednarek-Ochyra (2006). It is interesting that in 1995 Bednarek-Ochyra was emphatic that Bucklandiella was not separable at generic rank from Racomitrium in the broad sense, a position that has changed in the intervening years.
Racomitrium heterostichum; NOTE: left handed twist! Memaloose Park, Wasco Co., Oregon. DHW m0817i.
Racomitrium heterostichum; Irwin Rocks, Douglas Co., Oregon. DHW 7868.
Racomitrium heterostichum; Irwin Rocks, Douglas Co., Oregon. DHW 7868.
Racomitrium heterostichum; Red Ponds, Douglas Co., Oregon. DHW 7935.
Racomitrium heterostichum; Red Ponds, Douglas Co., Oregon. DHW 7935.
Racomitrium heterostichum; Memaloose Park, Wasco Co., Oregon. DHW m0817c.
Racomitrium heterostichum; Memaloose Park, Wasco Co., Oregon. DHW m0817c.
Racomitrium heterostichum; Memaloose Park, Wasco Co., Oregon. DHW m0817c.
Racomitrium heterostichum; Memaloose Park, Wasco Co., Oregon. DHW m0817c.
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Guide to Racomitrium of Oregon
Created 2007 Northwest Botanical Institute