Montana Field Guide

Linearleaf Moonwort is a small, perennial fern with a single pale green, above-ground frond which stands 6-18 cm tall. The frond is divided into two segments, one sterile, one fertile, which share a common stalk. The sterile segment is once-pinnate (with segments, or pinnae borne on each side of a elongated central axis) with 4-6 widely spaced pairs of pinnae which are linear shaped or sometimes bifid with linear lobes. The fertile segment is 1-2 times as long as the sterile segment and has a single major axis with short branches which bear grape-like sporangia which contain thousands of spores. Spores germinate underground and develop into minute, subterranean, non-photosynthetic gametophytes.

Frond probably maturing in August.

In Botrychium campestre the leaf rachis is broader and fleshy with the leaf segments closer together and sometimes overlapping. The individual segments are relatively shorter and broader with more divisions or lobes at the ends than in B. lineare. B. campestre also has a denser fleshy spore mass. Botrychium ascendens can also be quite similar, but the individual leaf segments are more strongly upright (ascending) and are generally more wedge-shaped, with the broader ends being more finely lobed or toothed. Unlike B. lineare, B. ascendens frequently bears some sporangia on the lower leaf segments.

Botrychium lineare is an early- to mid-succession species that has been found throughout its range in a wide variety of habitats. These include mid-height grasslands, grazed rangelands, a limestone shelf on a steep slope, a woodland trail, roadside gravels and in grass under conifers. Montana populations, with the exception of the historic Mission Mountain site in Lake County, which was found along a steep woodland trail, were all found along roadways in gravelly shoulders created during road construction. Most of the associated vegetation is low, allowing ample direct sunlight for much of the day.