(7) Rattlesnake FERN. Botrychium Virginiànum
Fronds six inches to two feet high. Sterile segment sessile above the middle of the plant, broadly triangular, thin, membranaceous, ternate. Pinnules lanceolate, deeply pinnatifid; ultimate segments oblong or lanceolate and scarcely or not at all spatulate. Fertile part long-stalked, two to three pinnate, its ultimate segments narrow arid thick, nearly opaque in dried specimens. Mature sporangia varying from dark yellow-brown to almost black. Open sporangia close again and are flattened or of a lenticular form. In rich, deciduous woods, rather common and widely distributed.
Prince Edward Island, Minnesota, south to Florida and Texas, and north to Newfoundland and Labrador.
Var. grácilis. A form much reduced in size.
Var. LAURENTIÀNUM. A conspicuous variety having thick and heavy sterile fronds less finely divided than the type, with the segments crowded to overlapping. Pinnules shorter than the type, tending to be ovate, outer segments strongly spatulate. Fertile spike relatively short and stout, strongly paniculate when well developed. Ultimate segments flat, folaceous, one mm. wide. Mostly confined to the limestone district near the Gulf of St. Lawrence, Labrador, Newfoundland, Quebec, Maine, and Michigan.
Var. INTERMEDIUM. Segments of sterile fronds ultimately much spatulate, previously ovate, not overlapping. Segments of fertile fronds ultimately narrowly flattened. (For this and the other varieties see Rhodora of September, 1919.) Nova Scotia, Maine, Vermont, Massachusetts, Connecticut, northern New York, Illinois, and Missouri.
Var. EUROPÀEUM. Fertile frond less finely dissected than in type. Ultimate segments more obtuse than in type; has but very slight tendency towards the spatulate form of the two previous varieties. Pinnules lanceolate, strongly decurrent so that the pinnæ are merely pinnatifid. In coniferous forests of Canada, and confined to calcareous regions. Quebec, New Brunswick, New Hampshire, Vermont, New York, Ontario, Montana, and British Columbia. Said to be rare even in Europe.