2. Sisyrinchium angustifolium Mill.
Pl.
92 g; Map 355
Aerial stems 15–50 cm long, 2–6 mm wide, often broadly winged, appearing
branched, not glaucous. Leaves 2–6 mm wide, not glaucous, sometimes darkening
upon drying. Inflorescences 1–4 per aerial stem, from often broadly winged
stalks 4–15 cm long from the axils of leaflike bracts. Spathelike bracts of
each inflorescence 1.3–4.0 cm long, green, sometimes purplish tinged, mostly
with the outer bract 1.5–2.0 times as long as the inner bract at flowering
time. Perianth pale blue to purplish blue. 2n=48. May–July.
Scattered throughout Missouri (eastern U.S. and adjacent Canada west to
Kansas). Mesic forests and stream banks, less commonly in mesic upland
prairies; also in old fields, on roadsides and ditch banks, and along railroad
tracks.
In Missouri, S. angustifolium can be difficult to distinguish from S.
atlanticum, particularly because some of the characteristics used to
separate these species in other portions of their ranges do not seem to work
consistently in the state. Missouri specimens of S. angustifolium darken
upon drying only sporadically, and are often a similar shade of green to those
of S. atlanticum when fresh. Although the stalks of the inflorescences
are broad-winged in most S. angustifolium plants, those of S.
atlanticum are not always uniformly narrow-margined, as has been described
elsewhere. In addition, S. atlanticum varies greatly in the degree of
glaucousness, and this characteristic is often lost when plants are pressed and
dried. The most reliable characters for separating the two species appear to be
the overall stem width and the size relationship of the 2 spathelike bracts, as
noted in the key to species above.
Ward (1968) discussed the application of S. angustifolium to our plants
instead of the previously widely accepted S. bermudiana L., which is
correctly applied to a species endemic to Bermuda.