Rare Species Guide

  Basis for Listing

Everything that is known about Polytaenia nuttallii in Minnesota is based on two herbarium specimens collected in the vicinity of Lanesboro in Fillmore County. One specimen is dated 1892 and the other is dated 1915, but no other useful information is contained in the specimen labels. Recent botanical surveys in Fillmore County, and adjacent counties, have failed to relocate this species. It is possible that a small, remnant population has been overlooked, but it is perhaps equally possible that this species is now extirpated from Minnesota. If it does survive in the state, it must be quite rare. In fact, it is considered rare, infrequent, or vulnerable in adjacent states, becoming at least somewhat common in the region of Missouri south to Texas (NatureServe 2009). Polytaenia nuttallii was listed as a special concern species in Minnesota in 1996.

  Description

Polytaenia nuttallii is a large perennial forb with thick taproots. The stems can reach 1 m (3.3 ft.) in height and branch above the middle. The blades of the lower leaves can be up to 18 cm (7.1 in.) long and 15 cm (5.9 in.) wide, and are divided in a pinnate-pinnatifid or bipinnate pattern. The upper leaves are mostly ternately divided. The individual leaflets are ovate to oblong, and have incised or lobed margins. The petioles of the lowest 2 or 3 leaves are 6-16 cm (2.4-6.3 in) long, while those of the upper leaves are much reduced or absent. The inflorescence is a compound umbel and it is terminal and axillary. Each umbel has 10-15 branches (rays) that are 2-3 cm (0.8-1.2 in) long. The flowers have yellow petals and are subtended by 1 to several linear, scarious bractlets. The fruits are glabrous, strongly flattened dorsally, oval to obovate or suborbicular in shape, 6-9 mm (0.24-0.35 in.) long, and 4-6 mm (0.16-0.24 in.) wide (Crawford 1970).

Members of this family (the carrot family) typically have small individual flowers that are arranged in umbels, and many have compound or deeply divided leaves. Polytaenia nuttallii differs from most of the others by having yellow flowers, a tall stem, evident sepals, and thick taproots. In southern Minnesota, it is perhaps most likely to be confused with the non-native Pastinaca sativa (wild parsnip), which has become an invasive weed in grasslands. However, the lower leaves of P. sativa are pinnate, meaning they are divided into distinctly separate leaflets. The leaves of P. nuttallii are pinnate-pinnatifid or bipinnate, which means the leaves are divided twice. In other words, the leaflets are themselves divided into leaflets.

  Habitat

Across its geographic range, P. nuttallii is considered a prairie species, but specifics are hard to come by. The paltry collection record for Minnesota is not much help; the two specimens collected in Fillmore County are not accompanied by any description of the habitat. There are a number of different types of prairies in Fillmore County, ranging from dry bluff prairies to wet lowland prairies. There are also savannas, which are upland prairies with trees or groves of trees scattered throughout. Some prairies have deep, fertile soil and others have thin, rocky soil. It's not certain what type of prairie P. nuttallii might find suitable in Minnesota, but based on information from other states, it seems likely that it would be somewhere in the middle of the moisture extremes; not too dry or too wet. Beyond that, not much can be said.

  Biology / Life History

Apparently, detailed aspects of the biology of P. nuttallii have not been studied, yet some generalizations can be inferred. For example, the root structure is indicative of a perennial, the floral structure indicates it is insect-pollinated, and the seed structure indicates it is probably animal-dispersed. As a prairie species, it is likely adapted to wildfires, although not all prairie species are so adapted.

The best time to search for P. nuttallii is when the flowers or fruits are present, from early June through August.

  Conservation / Management

It is important to settle the question of this species' current status in Minnesota. To do this will require a highly directed search of suitable habitat conducted by a seasoned and well prepared field botanist.

  Conservation Efforts in Minnesota

Because P. nuttallii has not been seen in Minnesota since 1915, no conservation efforts have been directed towards this species.

  References and Additional Information

Crawford, D. J. 1970. The Umbelliferae of Iowa. University of Iowa Studies in Natural History 21(4):1-37.

NatureServe. 2009. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia.