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Volume 76—1996

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Oklahoma Vascular Plants: Additions and Distributional Comments.

Constance E.S. Taylor1 Lawrence K. Magrath2, Patricia Folley3, Paul Buck4, and Sydney Carpenter5.

1 Biology Department, Southeastern Oklahoma State University, Durant, OK 74701
2 Biology Department, University of Sciences & Arts of Oklahoma, USAO Box 82308, Chickasha, OK 73018
3 Bebb Herbarium, 770 Van Vleet Oval, University of Oklahoma, Norman, OK 73019
4 Biology Department, University of Tulsa, Tulsa, OK 74104-3189
5 Oklahoma Chapter, The Nature Conservancy, 23 West Fourth, Suite 200, Tulsa, OK 74103

Received: 1996 Jan 02; Revised: 1996 Aug 02

Seven species of vascular plants are added to the flora of Oklahoma: Dioscorea oppositifolia, Lythrum salicaria, Momordica balsamina, Polygonum cuspidatum, Pyrus calleryana, Senecio vulgaris, and Verbena rigida. These species are either weedy invaders or escaped ornamentals. The re-collection of Epilobium coloratum, a native, and Mazus japonicus and Scutellaria cardiophylla is noted. The spread of two additional exotics, Fatoua villosa and Ligustrum sinense, is discussed.


Botanical field work in Oklahoma is documenting an increase in the number of species of vascular plants known to occur in the state. Taylor and Taylor (1) cited the discovery of 312 new taxa since Waterfall's list (2) was published in 1969. An additional seven new species, either weedy invaders or escaped ornamentals which are becoming established as part of the state's flora, are reported here. Taylor and Taylor's reported increase of 12.3% is similar to that of other states. The Flora of North America (3) reported the percentage of invading foreign species for 16 states as varying from 36% (New York) to 7% (Arizona). The widespread invasion of native floras by foreign species can be expected to continue. The objectives of this report are to document the seven new species, comment on the recollection of three previously reported exotics, including one collected once almost 60 years ago and thought to no longer exist in the state, and the spread of two non-native taxa.


In the listing below, the Herbarium at a particular institution is indicated as follows:

DUR Southeastern Oklahoma State University, Durant.
OCLA University of Science and Arts of Oklahoma, Chickasha.
OKL University of Oklahoma, Norman.
OKLA Oklahoma State University, Stillwater.
TUL University of Tulsa, Tulsa.


Dioscorea oppositifolia L. (Dioscoria batatas Decne.) Chinese Yam (Dioscoriaceae) Chinese yam is an herbaceous, perennial, twining vine, planted as an ornamental, escaping into fence rows, waste places, thickets and woods in the state. A native of Asia, it has been reported in Kansas (4).

Lythrum salicaria L. Spiked or Purple Loosestrife (Lythraceae). An herbaceous perennial introduced from Europe (5) it is escaping and becoming established in wet meadows, marshes, river floodplains and along the edges of lakes and rivers. The species is aggressive and is choking out native vegetation. A morphologically complex taxon, Lythrum salicaria is divided into numerous minor forms.

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Momordica balsamina L. Balsam-apple (Cucurbitaceae). Balsam-apple is an herbaceous, annual, vine that climbs via tendrils. Native to Africa and Asia (6), it was introduced into the western hemisphere as an ornamental and for its edible fruits. Correll and Johnston (7) reported that it had escaped and become part of the flora of Texas and Louisiana.

Polygonum cuspidatum Seib. and Zucc. Japanese Knotweed (Polygonaceae). Japanese knotweed is a rhizomatous, herbaceous perennial native to Japan (5). Initially introduced as an ornamental, it has escaped into neglected sites and waste places across much of North America. Bailey (6) indicated the species is hardy in northern states.

Pyrus calleryana Decne. Callery Pear, Bradford Pear (Rosaceae). Bradford pear is probably the most popular woody landscaping plant in Oklahoma in recent years. It is Chinese in origin (6) and of significant value to the horticultural industry. Pyrus is a polymorphic genus with identification of its species made troublesome by widespread hybridization and grafting. A population at an abandoned nursery near Durant is invading adjacent grasslands and roadsides. This suggests that the species is becoming independently established in the state.

Senecio vulgaris L. Groundsel (Asteraceae). Senecio vulgaris is an herbaceous annual and native to Eurasia (4). It has become naturalized over much of the U.S., primarily in well-watered, rich soils of roadsides, fields, and waste places (8).

Verbena rigida. Spreng. Tuber Vervain (Verbenaceae). Tuber vervain is an herbaceous perennial native to Brazil and Paraguay. Reported as an adventive member of the east Texas flora by Correll and Johnston (7), it has now been collected in Oklahoma.

Re-collected Species

Epilobium coloratum Biehler Willow-herb (Onagraceae). In Oklahoma, Epilobium coloratum is near the western edge of its range. Waterfall (2) stated that it was "...found once in Caddo Canyons" and based his comment on a 1938 collection by E.L. Little, Jr., 3996 (OKL) (9). The species is said to be infrequent to locally common (4) within its range and any documentation of its presence in Oklahoma is of interest.

Mazus japonicus Kuntze (Scrophulariaceae). Magrath and Taylor (10) first reported this Australasian exotic in Oklahoma from a 1978 collection in Idabel, McCurtain County. Recent re-collection of the species indicates it is spreading and becoming established.

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3264 (TUL) and 12 October 1995, BUck, 6362 (TUL)

Scutellaria cardiophylla Engelm. and Gray Heartleaf Skullcap (Lamiaceae). Correll and Johnston (7) reported this species in east Texas, Arkansas and western Louisiana. Its only other mention in regional floras is in Smith's treatment of the plants of Arkansas (11), but without any distribution information.

Spreading Exotics

Fatuoa villosa (Thunb.) Nakai (Moraceae). This species was initially reported in McCurtain County by Taylor and Taylor in 1981 (12). Fatoua is found as a weed under greenhouse benches in eastern Oklahoma and has been collected in Bryan and Tulsa Counties. It has become a nuisance and reportedly is controlled with herbicides.

Ligustrum sinense, Lour. Privet Hedge, Chinese Privet (Oleaceae). This species, a woody shrub native to China, is now a widespread and popular ornamental hedge plant in the U.S. (7). It persists along fence rows, abandoned home sites and waste places. It also has spread into moist forests and is apparently becoming an important member of the understory vegetation. Because it is evergreen, its presence is evident in mild winters.


1.   Taylor, R.J., and Taylor, C.E.S., An Annotated List of the Ferns, Fern Allies, Gymnosperms and Flowering Plants of Oklahoma. Herbarium, Southeastern Oklahoma State University, Durant, OK (1994) 133 pp.

2.   Waterfall, U.T., Keys to the Flora of Oklahoma. 4th ed. Oklahoma State University Bookstore, Stillwater, OK (1969) 246 pp.

3.   Flora of North America Editorial Committee. Flora of North America Vol. 1, Introduction. Oxford University Press, New York, NY (1993) pp. 193-198.

4.   Great Plains Flora Association, Flora of the Great Plains. University Press of Kansas, Lawrence, KS (1986) 1392 pp.

5.   Fernald, L.M., Gray's Manual of Botany. 8th ed, American Book Company, New York, NY (1950) 1632 pp.

6.   Bailey, L.H. The Standard Cyclopedia of Horticulture, Vols. 2 and 3, Macmillan Company, New York, NY (1942).

7.   Correll, D.S. and Johnston, M.C.,

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Manual of the Vascular Plants of Texas. Texas Research Foundation, Renner, TX (1970) 1881 pp.

8.   Steyermark, J.A. Flora of Missouri. Iowa State University Press, Ames, IA (1963) 1728 pp.

9.   Hopkins, M., Notes from the herbarium at the University of Oklahoma. Rhodora 40, 425-434 (1938).

10.   Magrath, L.K., and Taylor, J., Orchids and other New and Interesting Plants from Oklahoma, in New, Rare, and Infrequently Collected Plants in Oklahoma. Herbarium of Southeastern Oklahoma State University, Publication No. 2, Durant, OK (1978) 11 pp.

11.   Smith, E.B., Keys to the Flora of Arkansas. University of Arkansas Press, Fayetteville, AR (1994) 363 pp.

12.   Taylor, R.J., and Taylor, C.E., Plants new to Arkansas, Oklahoma, and Texas. Sida 9,25-28 (1981).