New Addition to the Southeastern Wisconsin Flora Part I

October Lady’s-tresses

Spiranthes ovalis var. erostellata Catling (Orchidaceae).

Inflorescence of October lady's tresses

Inflorescence of October lady’s tresses

October lady’s-tresses is generally a more southern species, but it may be extending its range northward, or “new” populations may have been overlooked in the past, because October lady’s tresses blooms, as its name implies, after most botanists have completed their surveys for the year.

Typical plant in habitat

Typical plant in habitat

October lady’s-tresses was first discovered in far southwestern Wisconsin in 1990. It had had not been found outside of that area in Wisconsin until this last October. While visiting Jericho Woods in Waukesha County this fall, the property owner showed me a small patch of orchids. At first I was confused by them, because they did not fit the description of any of the lady’s tresses species known from SE Wisconsin. However, when I sat down with my regional floras (Swink and Wilhelm, Gleason and Cronquist, Voss and Reznicek), it became clear very quickly that the plants were Spiranthes ovalis var. erostellata, the nearest known occurences of which are actually from DuPage and Kendall Counties in Northeast Illinois–still more than 100 kilometers away.

Basal and stem leaves

Basal and stem leaves

The population consisted of approximately 30 plants growing under a closed canopy of bur oak and American elm in association with a shrub layer dominated by common buckthorn and hybrid bush honeysuckle. The population was in peak flower on October 3, 2014.

October lady’s tresses is unique among the several lady’s tresses species in southern Wisconsin and the Chicago Region in having small, wholly white flowers, peak flowering in very late September / early October, a preference for shaded habitats, and an acute labellum (lower petal).

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One Response to New Addition to the Southeastern Wisconsin Flora Part I

  1. brvogt says:

    This is pretty cool, on many levels.

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