4402 Montia L.
- L., Sp. Pl.: 87 (1753).
- Montiastrum (A. Gray) Rydb. Fl. Rocky Mts.: 265, 1061 (1917). - Claytonia subsect. Montiastrum A. Gray, Proc. Amer. Acad. Arts 22: 283 (1887).
- Claytoniella Jurtz., Bot. Zhurn. 57: 644 (1972).
Notes: Yurtsev: Claytoniella and Montiastrum differ from Claytonia in quite distinctive pollen grains (Nilsson 1966, 1967), cristate seeds, and alternate leaves. Nilsson (1966, 1967) and Carolin (1993) included the species of Claytoniella in Montiastrum. We prefer to see these as different genera, as the two annual vernal plants of semiarid intermontane depressions in the western North American Cordilleras, recognized as Montiastrum s. str., are rather contrasting to the alpine-arctic perennial plants in many respects: morphological, cytological (base chromosome number, x = 7 in Montiastrum, x = 5 and 8 in Claytoniella), phenological, biological, as well as phytogeographic. There are good reasons to consider Montiastrum to be a descendant of Claytoniella having persisted the glacial maxima south of the Cordilleran Ice Sheet and transformed at one of the interglacials into the biological type of a vernal annual plant. The earliest (Late Pliocene) pollen of Claytoniella (after M. Grichuk) combines some features of C. kolymensis Jurtz. nom. nud. and the diploid Montiastrum dichotomum.
Elven and Murray: Miller (2003) included the relevant species in Montia. O'Quinn and Hufford (2005) presented convincing molecular evidence for inclusion of Montiastrum (including Claytoniella) in Montia.
Higher Taxa
- Montiaceae [44,family]