jhorthos's Journal

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L. glabrum has more rounded hypanthium (the basal part of the floral bract), where L. parviflorum has a distinct longer conical hypanthium that sometimes flares again at the rounded part (and is larger flowered despite the name parvi meaning small).

Plus L. glabrum flowers earlier in early spring (adamschneider) and the petals in L. glabrum are more deeply divided (sometimes almost looking like several petals for each of the five petals).

Number of petal lobes, number of flowers, leaf shape, and depth of petal division (deeper being L. glabrum) are helpful when the hypanthium is more elongate.

Only Cystopteris fragilis has prominent branching dark green veins visible from both sides of leaf, extending to the edge of the leaf.

Only Woodsia oregana has short glandular hairs on distal part of stem and the leaves (use hand lens, very small). If the hairs are longer it is W. scopulina.

There are differences in the young indusium but they are transient and subtle to my eye.

Quoted "yeah, exactly -- short hairs with glandular tips. Cystopteris will have basically no indument on the leaves, and have a characteristic-but-hard-to-describe look--mainly the leaves are thin, and you can see that the veins extend right to the leaf margin. If you can see the veins in Woodsia, you can see that they stop just short of the leaf margin in an expanded depression (hydathode). It can certainly be subtle..."