Botany Research

Iris virginica New to New York State

Iris virginica L., Southern Blue Flag
Restored to the Flora of New York State

P. M. Eckel, Buffalo Museum of Science, 1020 Humboldt Pkwy, Buffalo, N.Y. 14211
J. Bissell, The Cleveland Museum of Natural History, 1 Wade Oval, University Circle, Cleveland, Ohio 44106

In early spring of 1999 the first author was informed that a native species of Iris new to our region had been discovered by the second author along the Niagara River on Strawberry Island and Beaver Island State Park, New York. She immediately sent a recently collected specimen of Iris from Buckhorn Island State Park, in a marsh adjacent to the Niagara River, and the second author verified it also as Iris virginica.

The only Iris in the Rare Plant Status List for New York (Young 1997) was Iris prismatica Pursh, concentrated near the coast in eastern New York state. On the other hand, Mitchell and Tucker (1997) reported Iris virginica var. shrevei (Small) Anders. in the state checklist, as endangered, indicating that no known extant sites occur in the state (that is, it was considered extirpated).

Iris virginica var. virginica occurs on the southern coastal plain, and the var. shrevei is a name used of inland stations. The only other native Iris reported for the western New York counties has been Iris versicolor L., although Iris virginica (without variety) was noted for the Province of Ontario by Morton and Venn (1984). Voss (1972) reported Iris virginica [= var. shrevei] as very common throughout Michigan south of the Northern Peninsula. Iris versicolor has fewer records, and these derived from the central to northern part of that state, suggesting a northern affinity.

The second author previously had found Iris virginica in the early 1990s within riverine wet-lands along Lake Erie in Pennsylvania where he reported it from Presque Isle as new to that state in 1993. In subsequent years, he found it at additional stations in Pennsylvania and inland along the Conneaut Creek. The plant becomes common inland west of Cleveland, but is generally restricted to Lake Erie marshes east of that city. Records now occur for every northern Ohio county including wetlands associated with Lake Erie. He also was aware of its occurrence at Long Point in the Regional Municipality of Norfolk-Haldimand (Reznicek & Catling 1989).

Although these are areas mostly adjacent to Lake Erie, Voss’ Michigan maps (1972) indicate inland stations in nearly every county in “Ponds and lake shores, marshes and swales, ditches, stream sides, riverbanks and thickets, swamp forests, and rarely bogs,” suggesting that perhaps some inland reports of Iris versicolor in western New York and the Regional Municipality of Niagara may be Iris virginica instead. The marshes along the Niagara River are similar to those at Long Point and Presque Isle, strongly indicating the likelihood of Iris virginica occurring there.

Iris virginica is rather tricky to identify, especially from herbarium material. The best character to use in distinguishing it from Iris versicolor is the length of the ovary, and some of us may be confused as to where this ovary is on our specimens. The 6 tepals (petals and sepals) in the genus Iris are perched just above the mouth of the ovary, so the ovary is beneath the petals (epigynous). The ovary length is the length of this spindle-like structure from beneath the petals to a constriction just above the stalk on which the ovary develops (it is good to have a specimen to look at to see this). The ovary is large in I. virginica (1.8-3 cm), and smaller in I. versicolor (1-2 cm). The other good character is the nature of the colored spot on the sepal: see below. With some experience in the field, it will be noted that Iris virginica is a much more robust plant than is Iris versicolor.

Iris virginica: OVARIES AT FLOWERING TIME (before fruit set) 1.8-3 cm LONG; base of expanded portion of SEPAL WITH A BRIGHT (not dull) YELLOW SPOT, FINELY PUBESCENT (not only papillate). Later in the year seeds round to D-shaped, irregularly and variously shallowly to deeply pitted.

Iris versicolor: OVARIES AT FLOWERING TIME SMALLER, 1-2 cm LONG; base of ex-panded portion of SEPAL WITH DULL GREENISH-YELLOW SPOT (not bright yellow), the shallow papillae shorter than the thickness of the sepal (not pubescent with hairs). Seeds D-shaped, with a more or less regularly and finely surface.

Voucher specimens of Iris virginica are deposited in the herbaria of the Buffalo Museum of Science (BUF) and the Cleveland Museum of Natural History (CLM).

We encourage members of the Botanical Society to pay particular attention to streamside blue irises in the coming field season. Local reports and specimens can be mailed or dropped off for verification or deposit in the herbarium at the Buffalo Museum of Science, attn. Botany Division.

Acknowledgements:
The authors would like to thank Paul Leuchner of the Army Corps of Engineers for information provided in support of this discovery.

Mitchell, Richard S. & Gordon C. Tucker. 1997. Revised Checklist of New York State Plants. New York State Museum Bulletin 490.

Morton, J. K. & Joan M. Venn. 1990. A Checklist of the Flora of Ontario Vascular Plants. University of Waterloo Biology Series No. 34. Obtainable from Department of Biology, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1.

Reznicek, A. & P. M. Catling. 1989. Flora of Long Point, Regional Municipality of Haldimand-Norfolk, Ontario. The Michigan Botanist Vol. 28(3): 99-175.

Voss, Edward G. Michigan Flora. 1972. Part I. Gymnosperms and Monocots. Cranbrook Institute of Science Bulletin 55 and University of Michigan Herbarium, Ann Arbor.

Young, Steven, ed. 1997. New York Rare Plant Status List. New York Natural Heritage Program. Latham, New York. March.