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Prenanthes nana (Bigelow) Torr.

Photo: Prenanthes nana

Dwarf Rattlesnake Root

Habitat: Rocky or mossy exposed places in alpine areas. [Alpine or subalpine (non-forested, upland)]

Range: Northern New York to Newfoundland.

Aids to Identification: This rattlesnake root can be distinguished from other Prenanthes species by the following characteristics: bracts beneath the flowers are greenish-black to black and hairless; lower leaves are deeply lobed; there are 9-12 yellowish-white flowers; and it is found in alpine areas. It closely resembles a dimunitive version of the common rattlesnake root (P. trifoliolata). The closely related, and frequently co-occurring P. boottii has basal leaves that may be sagittate, but not lobed, with stems that are often hairy in the upper portion (the stems of P. nana are glabrous, or hairless).

Photo: Prenanthes nana flower

Ecological characteristics: All Maine occurrences of this species have been found in high elevation exposed areas on inland mountains.

Phenology: Flowers July - August.

Family: Asteraceae

Synonyms: Known as Nabalus trifoliatus Cass. Formerly known as Prenanthes trifoliolata (Cass.) Fern. var. nana (Bigelow) Fern., or in some very old treatments as Nabalus nanus (Bigelow) DC.

Known Distribution in Maine: This rare plant has been documented from a total of 12 town(s) in the following county(ies): Hancock, Knox, Oxford, Piscataquis, Somerset, Washington.

Dates of documented observations are: 1896, 1897, 1902, 1909, 1911, 1928, 1931, 1941, 1950, 1951, 1953, 1969, 1994

Reason(s) for rarity: At southern limit of range.

Conservation considerations: Populations could be threatened by heavy recreational (hiking) use.