Rare Species Guide

  Synonyms

Polygonum careyi

  Basis for Listing

Persicaria careyi is one of the mystery plants of Minnesota. It was discovered near Holyoke in Carlton County in 1940, and never seen again. To this day, it can't be said with any degree of certainty whether it still occurs in Minnesota. It may have existed in the state as a transient population that has since disappeared, or it may still be out there waiting to be rediscovered. Until a concerted effort is made to identify potential habitat and conduct a thorough search, its status must remain in the rather ambiguous "special concern" category.

Minnesota is not alone in examining the status of P. careyi. Many other states and Canadian provinces consider it rare, endangered, or threatened (NatureServe 2009). Although it is perhaps speculative to make a prediction, if a viable population were to be found in Minnesota, it would be a likely candidate for endangered or perhaps threatened status.

  Description

Persicaria careyi is an annual with an erect, leafy stem that may reach 1.5 m (4.9 ft.) in height. The upper portion of the stem and the peduncles have stalked glands, which are important for identification. At each node there is a hairy, reddish brown ocrea (a tubular stipule that encircles the stem) with a margin of bristles 2-7 mm (0.08-0.28 in.) long. The leaf petiole is 0.5-1.5 mm (0.02-0.06 in.) long and hairy. The leaf blade is 6-18 cm (2.4-7.1 in.) long, 1-3.5 cm (0.4-1.4 in.) wide, and narrowly lanceolate in outline with a narrowly pointed tip. Both the terminal and axillary inflorescences are spikelike. They tend to nod or droop and are usually interrupted, meaning there are gaps between some of the flowers. The flowers are purple or rose-color and non-glandular. The achenes are smooth and shiny, dark brown to black.

  Habitat

Persicaria careyi has been found only once in Minnesota, and the habitat at that site was not recorded. Elsewhere in its range, it occurs in a variety of moist to wet habitats such as sandy shores (Keddy and Reznicek 1982), meadows, riverine habitats, and seasonally wet depressions in peatlands (Cohen and Kost 2007). Occurrences tend to be on acidic substrates, predominately sandy, silty, or clayey materials or possibly peaty or organic sediments. These might be early successional habitats or small areas of recent disturbance in otherwise late successional habitats.

  Biology / Life History

Persicaria careyi is an annual forb that seems to specialize in early-successional wetland habitats where competition is minimal. An example of one such habitat is the draw-down zone of shallow lakes and ponds. A study in Ontario (Keddy and Reznicek 1982) documented a large population of P. careyi on a sandy lake shore that was exposed for one year during a low-water phase. The study also found a persistent bank of P. careyi seeds in the lake bottom, reaching a maximum abundance at a depth of 90 cm (3 ft.). From this, the authors concluded that P. careyi would be part of a rich flora that would germinate if the sediments were exposed. It seems likely that a seed bank might develop in marsh or meadow habitats as well as lake shores, and that water fluctuations could be the result of beaver activity as well as weather patterns. It is also possible that buried seeds could be exposed by wildfire, animal digging, or scraping. Since the seeds themselves apparently do not float on water, and they are too heavy to be carried on wind currents, long-distance dispersal of seeds (e.g., movement from one watershed to another) probably occurs through the gut of small mammals or birds.

The best time to search for P. careyi would be when the flowers/fruits are mature in August and the first part of September.

  Conservation / Management

As of 2009, there were no known extant populations of P. careyi in Minnesota, so specific guidelines cannot be developed at this time. Targeted searches are needed to try to gain a better understanding of the habitat, distribution, and life history of this poorly known species.

  Conservation Efforts in Minnesota

Because no extant populations of P. careyi have been found in Minnesota, no conservation efforts have been directed towards this species.

  References and Additional Information

Cohen, J. G., and M. A. Kost 2007. Natural community abstract for intermittent wetland. Michigan Natural Features Inventory, Lansing, Michigan. . Accessed 5 November 2009.

Hinds, H. R., and C. C. Freeman. 2005. Persicaria. Pages 574-594 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 5. Oxford University Press, New York, New York.

Keddy, P. A., and A. A. Reznicek. 1982. The role of seed banks in the persistence of Ontario's coastal plain flora. American Journal of Botany 69(1):13-22.

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