Leaves and stems:

The sterile leaf, called a trophophore, is single near the top of the stem, triangular in outline with up to 5 pairs of leaflets (pinnae) that are lance-oblong in outline and divided into narrow lobes, the lowest (basal) pinnae largest becoming smaller as they ascend the stalk. The basal pinnae are sometimes further divided, making the trophophore appear twice compound with 3 main leaflets. The trophophore is stalkless, up to about 2½ inches long and wide, held ascending or more often perpendicular to the stem, and is shiny to dull dark green. 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 to 2½ times as long as the trophophore and rising above it at the end of a short stalk. The sporophore is usually divided into 3 prominent branches (occasionally more), the branches often about equal in length and each with a few to numerous smaller side branches. Spores develop all along the branches in small, round capsules (sporangia) that turn yellow when mature in July and August.

Notes:

Botrychium angustisegmentum, also known as B. lanceolatum subsp. angustisegmentum, may be the easiest Minnesota Botrychium species to identify. Its sporophore is usually divided into 3 main branches, its trophophore is stalkless, triangular in outline, typically forms a 90° angle with the common stem, and the stem is maroon-tinged, especially at the base. Most similar would be a robust specimen of Botrychium matricariifolium, with which it may grow side by side, but its trophophore is usually stalked and held ascending to nearly erect. The reddish stem is a trait shared only with these two species plus Botrychium michiganense, which does not have deeply divided pinnae except for the basal pair. As with all Botrychium species, examination of several specimens in a population is often needed for a positive ID and consultation with an expert may ultimately be required.

According to the DNR, Botrychium angustisegmentum was first collected in Morrison County in 1918, then not again until 1991. While subsequent biological surveys located a number of additional sites, populations are small and its forest habitat is under threat from logging and other disturbances, as well as invasive species such as earthworms, garlic mustard, and buckthorn. It was listed as a state Threatened species in 1996.