Botrychium presents particular identification problems because often extremely small plants are fertile; these being determinable only in the context of the larger plants with which they are growing. In addition, mixed colonies are not uncommon, so care needs to be taken to sort plants. Plants growing in unusually shaded habitats may also be quite divergent in apearance from sun forms.
1. Vegetative blades linear to linear-oblong, simple to lobed, lobes rounded to square and angular, stalks usually 1/2 to 2/3 length of vegetative blade; plants in deep shade, filtered light under shrubs and trees, or (B. simplex and sometimes B. tenebrosum) in open grassy fields.
2. Segments of vegetative leaves rounded, margins mostly entire; plants herbaceous in texture, green; habitats various, in forests or open ground.
3. Fork into fertile and sterile segments occurring from about 1/5 to 1/2 the total height of the plant (measured from the stem base); at least well-developed pinnae longer than wide, tapering to a narrow attachment point, the lowermost pair usually clearly larger than the rest, or the lowest pair of segments themselves pinnate; peduncle of the fertile segment often 1-3 times the length of the entire vegetative segment.
3. Fork into fertile and sterile segments occurring from about 1/2 to 4/5 the total height of the plant (measured from the stem base); most pinnae wider than long, with a broad attachment area almost the width of the entire pinna, basal pinnae no larger than the rest; peduncle of the fertile segment usually 1/3 to 1 1/2 times the length of the entire vegetative segment.
2. Segments of vegetative leaves angular, outer margins often coarsely dentate; plants ± succulent; shiny yellow-green; in shady forest understories, often concealed by leaf litter.
1. Vegetative blades linear to deltate (narrowly oblong in B. minganense), pinnate (whether looking at lobes or actual pinnae), lobes of varying shapes, stalk usually less than 1/4 length of vegetative blade; plants frequently in open habitats; dunes, stream banks, road banks, on trails and openings in forests, etc.
4. Basal pinnae or segments of vegetative blade with venation like the ribs of a fan, usually with less than 14 veins terminating at each segment/pinna margin; midrib absent.
5. Basal pinnae broadly fan-shaped (almost perfect half moons) with narrow stalks.
5. Basal pinnae narrowly fan-shaped, or cuneate to lanceolate or linear.
6. Vegetative blades at least partially folded longitudinally when alive (conduplicate), usually not more than 4 cm long by 1 cm wide; pinnae up to 5 pairs; basal pinnae usually 2-cleft.
7. Vegetative blades very fleshy; fertile portion of blades usually less than 1.5 times the length of vegetative blades; pinnae mostly linear; basal pinna lobes ± equal; appearing in late May.
7. Vegetative blades herbaceous; fertile portion of blades usually 1.5–4 times the length of vegetative blades; pinnae asymmetrically fan-shaped; basal pinna lobes unequal; appearing in mid-June or later.
6. Vegetative blades flat or folded only at base when alive, usually up to 10 × 2.5 cm; pinnae up to 10 pairs; basal pinnae unlobed, or if lobed, not usually 2-cleft.
8. Vegetative blades narrowly oblong (maximum width of vegetative blade occurring at the level of one or more pinna pairs above the base), firm to herbaceous; pinnae fan-shaped, margins shallowly crenate; proximal fertile portion of blade branches 1-pinnate.
8. Vegetative blades narrowly deltate (maximum width of vegetative blade at level of basal pinnae); pinnae spatulate to linear spatulate, margins entire to very coarsely and irregularly dentate; most proximal fertile portion of blade branches usually 2-pinnate.
4. Basal pinnae or segments of vegetative blade with pinnate venation, with 14 or fewer veins terminating at the pinna/segment margin; midrib present.
9. Fertile portion of blade unbranched or with loosely pinnate branches smaller than the single main axis.
9. Fertile portion of blade tripartite, with three major branches from near base of stalk at sessile vegetative blade.
10. Vegetative blade deltate, with extremely short rachis, or rhomboid in less common leaves with longer rachis; margins dentate throughout; mostly in forests; occasional in other habitats.
10. Vegetative blade ovate or oblong to linear with (usually) exaggerated basal pinnae; remaining pinnae ± entire-margined; dunes and inland areas of sand, occasional in forests.