Torreyochloa pallida    (Torr.) Church

Torrey's Mannagrass 


MN Status:
special concern
Federal Status:
none
CITES:
none
USFS:
none

Group:
vascular plant
Class:
Monocotyledoneae
Order:
Cyperales
Family:
Poaceae
Life Form:
graminoid
Longevity:
perennial
Leaf Duration:
deciduous
Water Regime:
wetland
Soils:
muck
Light:
full sun, partial shade
Habitats:

(Mouse over a habitat for definition)


Best time to see:

 Foliage Flower Fruit 
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Torreyochloa pallida Torreyochloa pallida Torreyochloa pallida

Click to enlarge

Torreyochloa pallida
Minnesota range map
Map Interpretation
North American range map
Map Interpretation

  Synonyms

Puccinellia pallida, Glyceria pallida, Glyceria fernaldii, Puccinellia fernaldii

  Basis for Listing

There are two recognized varieties of Torreyochloa pallida occurring in Minnesota: T. pallida var. fernaldii (Hitchc.) Dore and T. pallida (Torr.) Church var. pallida. Torreyochloa pallida var. fernaldii is primarily a northern species ranging across portions of Canada and south through the upper Great Lakes states to greater New England. Torreyochloa pallida (Torr.) Church var. pallida ranges primarily in the northeastern U.S. and Canada, occurring westerly to Manitoba and Minnesota and south to Missouri and Georgia.

The earliest documentation of T. pallida in Minnesota is a 1929 record from an ash swamp near the Clearwater/Hubbard county border. The species was not reported again until 1980, where it was found growing along a pond edge in Pine County, and then not again until 1997 when it was documented from Cook County in extreme northeastern Minnesota. Since then, the number of documented locations has increased significantly; as of 2008, T. pallida had been reported from over 100 locations. The vast majority of these occurrences are from the Arrowhead region of Cook, Lake and St. Louis counties, although the species is also known to occur in Itasca, Otter Tail, and Carlton counties.

It is not known why T. pallida was poorly reported in Minnesota for so many years as the species is quite distinct and often occurs in large populations. Although we are gaining a better understanding of the species' distribution in Minnesota, many T. pallida collections have not been determined to variety. Torreyochloa pallida was listed as a special concern species in Minnesota in 1996.

  Description

Torreyochloa pallida is a perennial grass with decumbent stems that typically root at the lower nodes. The leaf sheaths are open to the base. The inflorescence is a terminal panicle; the lower glume is 1(3) nerved and the upper glume is (1)3(5) nerved. The lemmas are membranous and strongly (5)7-9 veined. Specimens of T. pallida that fit var. fernaldii have cauline leaves that are 1.5-3 mm (0.06-0.12 in.) wide with anthers of the lowest floret of each spikelet that are 0.3-0.6 mm (0.012-0.024 in.) long. Specimens of T. pallida that fit var. pallida have cauline leaves 2.8-9(11.4) mm (0.11-0.35 in.) wide with anthers of the lowest floret of each spikelet that are 0.7-1.5 mm (0.028-0.06 in.) long (Davis 2007).

Torreyochloa is similar to species of Glyceria and Puccinellia. Species of Glyceria however, have closed leaf sheaths and species of Puccinellia have (3)5(7) lemma veins. One species of Torreyochloa, four species of Glyceria, and two species of Puccinellia are known to occur in Minnesota.

  Habitat

Torreyochloa pallida occurs in a wide variety of wetland habitats including the shores and shallows (0.3-0.9 m; 1-3 ft.) of streams, lakes, vernal ponds, and beaver ponds. Water is often slower moving and substrates are typically mucky. The species also occurs in Fraxinus nigra (black ash) swamps and bogs (poor fen). Associated plant species include Glyceria canadensis var. canadensis (rattlesnake grass), G. grandis var. grandis (tall manna grass), G. striata (fowl manna grass), Sium suave (water parsnip), and Calla palustris (wild calla).

Across its range, T. pallida is known to occur in swamps, marshes, bogs, and the margins of lakes and streams (Davis 2007); and wet creek borders, alder thickets, wet coniferous thickets, pond borders, wet hollows in woods, bogs, and cattail marshes, often in shallow water (Voss 1972).

  Biology / Life History

Torreyochloa pallida is a perennial grass and an obligate wetland species in Minnesota (Milburn et al. 2007). It occurs as both scattered, small patches of plants and as large, robust colonies of 1,000s of culms. The species propagates by seed and vegetatively by rhizomes. The rooting nature of the culms may also allow broken and dislodged portions of the plants to further establish themselves. The decumbent growth form and rooting culms are distinctive when observed growing as loosely tangled mats along the sunny, mucky shores and shallows of slow moving streams.

The best time to observe T. pallida is mid-July to mid-August when it is typically in prime flower and fruit.

  Conservation / Management

Although detection of T. pallida and documentation of its distribution in Minnesota has improved, we know little more regarding the species' biology and how populations are responding to management activities and a changing environment. Potential threats to T. pallida include outright habitat destruction and physical, chemical, or hydrological alterations of habitat conditions. Ample opportunity exists across land ownerships to learn more about the dynamics of this wetland species.

  Conservation Efforts in Minnesota

While most T. pallida populations occur on state and federal land, few occur in areas that are formally protected and designated, such as Scientific and Natural Area, State Parks, or the Boundary Waters Canoe Area Wilderness.

Many of the Minnesota T. pallida herbarium specimens remain to be further studied to determine specific variety type. Accurate identification is essential to clarify the abundance, distribution, and habitat preferences of T. pallida var. fernaldii and T. pallida var. pallida in Minnesota. Based on these results, more specific conservation actions may be warranted.

  References and Additional Information

Davis, J. I. 2007. Torreyochloa. Pages 607-609 in Flora of North America Editorial Committee, editors. Flora of North America North of Mexico. Volume 24. Oxford University Press, New York, New York.

Milburn, S. A., M. Bourdaghs, and J. J. Husveth. 2007. Floristic quality assessment for Minnesota wetlands. Minnesota Pollution Control Agency, St. Paul, Minnesota. 197 pp.

Voss, E. G. 1972. Michigan Flora: Part I Gymnosperms and Monocots. Cranbrook Institute of Science Book 55, Bloomfield Hills, Michigan. 488 pp.