Leaves and stems:

The sterile leaf, called a trophophore, is single near the top of the stem, egg-shaped to oblong in outline with up to 7 pairs of leaflets (pinnae). Pinnae size and shape is highly variable but the lowest (basal) pinnae are typically largest, sometimes dramatically longer than the pair above it, and often deeply divided into narrow to broad, rounded lobes. Veins branch off a midrib, most distinct on the basal pair and often more obscure on upper pinnae.

Pinnae above the basal pair may become progressively smaller, or all be of similar size, and either divided like the basal pair or more sparingly notched or shallowly toothed, with incisions usually on both the upper and lower edge of the pinnae. Shape is oblong to nearly round, often broadest above the middle and rounded to square to pointed at the tip.

The trophophore is up to about 4 inches long, held ascending to erect, usually stalked to about 10mm (3/8 inch), and is powdery green to green in color. The stem is smooth and commonly red to maroon-tinged especially near the base.

Spores:

At the top of the stem is the fertile frond, called a sporophore, 1.3 to 2.4 times as long as the trophophore and rising above it at the end of a stalk that is shorter than the trophophore. The sporophore may be undivided with a few to numerous slender side branches.

It may also be divided into 2 or 3 (or more) main branches, each with side branches. Spores develop all along the branches in small, round capsules (sporangia) that turn yellow when mature in June and July.

Notes:

Botrychium matricariifolium is the most common Botrychium species in Minnesota. It can occur in populations of hundreds of plants, and is generally the easiest to spot. It is also one of the most variable, which can make identification challenging. In deep shade it may appear weak and spindly while in open, sunnier spots is much more robust. B. matricariifolium plants that have an oblong trophophore may resemble a number of other species, but careful examination of the pinnae should show a midrib where other species of a similar form have veins in a fan-shaped pattern (see photo below), plus these others would lack any red coloring on the stem.

B. matricariifolium plants with all deeply divided pinnae may resemble Botrychium angustisegmentum, with which it may grow side by side, but the latter's trophophore is stalkless, triangular in outline and more often held perpendicular to the stem. When the basal pinnae of B. matricariifolium are disproportionately larger than the pair above, it strongly resembles Botrychium michiganense, with which it may also grow, but which usually has a stalkless trophophore, and, except for the basal pinnae, its pinnae are often smooth along the edges or are shallowly cut mostly on the lower edge (see photo below). The reddish stem is a trait shared only with these 3 species, but, as with all Botrychium species, examination of several specimens in a population is often needed for a positive ID, and an expert consultation may ultimately be required.