Adiantum aleuticum var. aleuticum
(synonym of Adiantum pedatum)
Adiantum jordanii
northern maidenhair fern, western maidenhair fern
California maidenhair fern
short creeping and branched;
scales abundant, brown; to about 3 mm long.
few to numerous, loosely clustered; to about 80 cm long but usually much shorter, herbaceous; pale to medium (yellow-) green.
variable in length and rather brittle; up to about 50 cm and much longer than the blade to much shorter than the blade; purplish black, scaly at the base; otherwise glabrous or with a few scales;
rachis similar to and continuous with the petiole.
(broadly) lanceolate, pinnate (bipinnate); to 28 × 10 cm, arching or pendulous; lower pinnae (2)3(4)-pinnate.
fan-shaped; leaf-like; up to 1.5 × 2 cm;
distal margins of fertile segments more or less regular, shallowly and sparsely incised between the false indusia less than 25% of the way to base, margins of non-fertile segments more lobed or toothed;
base truncate to obtuse;
stalk purple-black, 1–4 mm.
linear; up to about 1 cm long; pale, often forming a white band along the curved distal leaf margin.
borne on and under the false indusium.
=60.
Adiantum aleuticum var. aleuticum
Adiantum jordanii
[After the publication of volume 1, Flora of Oregon, we accepted this variety. The treatment of this taxon in volume 1 corresponds to Adiantum aleuticum.]
Rocky steam banks, seepage areas. 100–500 m. Sisk. CA; Baja California. Native.
In California, A. jordanii hybridizes with A. aleuticum to produce a sterile hybrid, A. × tracyi, and this hybrid is likely to be found in southwestern Oregon where the ranges of the two species overlap. The appearance of the leaf segments is intermediate between the parents, and the distal half of the leaf blade is unbranched in A. × tracyi, while in A. jordanii all except the last few pinnae are at least bipinnate.
Duncan Thomas
OR
Flora NW
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
CA
