Clevea hyalina
| Common Name | Hyaline Liverwort |
| Frequency | Infrequent |
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Distinguishing Features
When fertile, this complex thallose liverwort is easy to recognize on account of the translucent white scales emerging from the undersides at the thallus margin in combination with the deeply divided, 2-4 armed, star-shaped carpocephalum (see photos). It thrives on fine mineral soils, especially along rock ledges or under overhangs. Antheridia and archegonia are borne on separate plants (dioicous) and the openings on the upper surface of the thallus are star-shaped.
Similar species
White scales that protrude along the margins of a thallose liverwort are not seen in many species. Species in the genus Riccia can have white scales along the margin, but plants of that genus have a prominent furrow down the middle of the thallus and sporophytes that are embedded in the thallus. In Clevea, the thallus is not furrowed and the sporophytes are borne on a specialized carpocephalum that emerges from and sits well above the thallus. Mannia fragrans can grow in similar habitats and the tips of its scales can be white, but they show purple pigmentation near their base. Furthermore, that species has a hemispherical carpocephalum, antheridia that are cloistered together on a differentiated pad and an upper surface with air chamber openings that are encircled by two rings of surface cells. In Clevea, the openings of the air chambers on the upper surface are star-shaped and lack encircling rings of cells, antheridia are scattered along the thallus and the carpocephalum has distinct segments. The two other genera of Cleveaceae known to occur in the Pacific Northwest are both arctic-alpine in distribution and both can have white scales. Sauteria alpina differs in having antheridia and archegonia present on the same plant (“monoicous”) and a rounded carpocephalum compared to the clearly lobed carpocephalum of Clevea hyalina, a species that has its antheridia on separate plants from said carpocephalum. Peltolepis quadrata has a carpocephalum that emerges from a notch at the edge of the thallus and bears 3-8 lobes, whereas the carpocephalum of C. hyalina emerges from the middle of the thallus and has 2-4 lobes. Antheridia, when present, are diffuse on the thallus of Clevea, while in P. quadrata, they are cloistered into a small pad.
Habitat
Moist, shady mineral soil, rock outcrops, and cliffs, often where calcareous, in the lowland, montane, and subalpine zones; infrequent in sw and n [east to the Rocky Mts.] BC, rare in sc, c, and se BC.
Associated species
Distribution Map
Relevant Literature
- Godfrey, J.D. (1977). Hepaticae and Anthocerotae of southwestern British Columbia . [Doctoral dissertation, University of British Columbia]. UBC cIRcle.
- Hong, W. S. (2007). Scapania. In Flora of North America Editorial Committee (Eds.), Flora of North America North of Mexico (Vol. 3) . Oxford University Press.
- Wagner, D. H. (2013). Guide to the liverworts of Oregon: Scapania undulata . Oregon State University Herbarium.