Rare Species Guide

  Basis for Listing

Paronychia fastigiata var. fastigiata (forked chickweed) is an inconspicuous annual of open sandy woods that is endemic to the eastern half of the United States. It is not reported to be particularly rare or declining over its entire range, but it does appear to be quite rare in Minnesota, which is at the northwestern periphery of its range. It was discovered here in 1976 near Afton in Washington County, followed by another discovery in 1981 only a few kilometers away (St. Paul-Baldwin Plains and Moraines Subsection). Its discovery was unexpected, and it was believed that additional searches were needed to determine its status. For that reason, in 1984 it was given a provisional status of special concern. Further searches were conducted but failed to locate any additional occurrences. The very limited number of known locations in Minnesota makes its future in the state very tenuous. For these reasons P. fastigiata var. fastigiata was reclassified as endangered in 1996.

  Description

Paronychia fastigiata var. fastigiata is a small annual, only 5-25 cm (2-10 in.) tall. The leaves of the primary branches are 5-20 mm (0.2-0.8 in.) long and frequently covered with white dots. The leaf bracts extend through the repeatedly forked, rounded or flat-topped flower clusters. Paronychia fastigiata var. fastigiata can be distinguished from closely related P. canadensis (Canada forked chickweed) by the puberulent (covered with fine short hairs) stems and a calyx (outer part of the floral envelope) that is 2-3 mm (0.08-0.12 in.) long.

  Habitat

Over most of its range P. fastigiata var. fastigiata is found in dry woods and openings. Minnesota populations have been found in open sandy ground and on a southwest-facing bank in a partially shaded deciduous forest. Suitable habitat might be found in sand savannas.

  Biology / Life History

Paronychia fastigiata var. fastigiata is a small herbaceous annual with tiny insect-pollinated flowers. Specific pollinator species have not been reported in the botanical literature but likely include a variety of very small non-specialized flying insects. The seeds are also very small and possess no obvious mechanisms for long-distance dispersal. It is likely that short-distance dispersal is facilitated by small ground-foraging animals, possibly including mammals, birds, and insects. Seed dormancy has not been reported for this species, but the seeds of most annual species germinate sporadically over a number of years, often developing a bank of dormant yet viable seeds in the soil. In such cases, a flush of germination may occur when environmental conditions are particularly favorable for seedling development. Such conditions may be triggered by unusual weather events, such as a particularly wet or dry spring or unusual temperature fluctuations. Fire or soil disturbance, such as animals burrowing or digging, may also stimulate germination. As is the case with all annual species, each individual will flower and produce seeds each year then die at the end of the growing season.

  Conservation / Management

Paronychia fastigiata var. fastigiata is usually associated with sand savannas or sparsely vegetated openings in early successional forests. These habitats were originally maintained by frequent wildfires, but active fire suppression has interrupted this cycle. Alternative management strategies must be used to maintain these habitats. So far, conservation efforts have concentrated on brush removal using heavy machinery and prescribed burning. On sites where P. fastigiata var. fastigiata occurs, burn units should be designed to avoid burning all occupied habitat in any one year. Use of heavy machinery should be avoided during the growing season.

  Best Time to Search

The best time to search for Paronychia fastigiata var. fastigiata is when reproductive structures are present from early July until mid-September.

  Authors/Revisions

Welby R. Smith (MNDNR), 2020

(Note: all content ©MNDNR)

  References and Additional Information

Core, E. L. 1941. North American species of Paronychia. The American Midland Naturalist 26:369-397.

Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis. 320 pp.

Ownbey, G. B., and W. R. Smith. 1988. New and noteworthy plant records for Minnesota. Rhodora 90:369-377.

Schlising, R. A., and H. H. Iltis. 1961. Preliminary reports on the flora of Wisconsin. No. 46. Caryophyllaceae - pink family. Pages 89-139 in S. D. Beck, editor. Transactions of the Wisconsin Academy of Sciences, Arts and Letters. Volume LI. Wisconsin Academy of Sciences, Arts and Letters, Madison.