Even though Linum medium var. texanum is a variety of the species, the variety medium has double the chromosome number (n=36 verses n=18) and could be treated better as a separate species (Harris 1968). Variety texanum was described based on a specimen from Texas even though it is at the edge of its range there (Fernald 1935).
There are nine existing populations but only four of them are ranked good to excellent. Most populations have fewer than 100 plants and are threatened by succession or lack of proper management. There are 10 historical populations, but most of these occur in highly developed areas so the probability of relocating them is low.
The short-term trends seem stable to slightly declining as most existing populations have not had dramatic changes in the last 20 years. There are a couple of populations that have been checked again and their numbers were down from previous years.
During the last 80 years populations on Western Long Island have disappeared while new populations were found in central and eastern Long Island in the last 20 years. This species has never been common in New York with population numbers hovering around 10 statewide.
Populations are threatened by direct development of their habitat and by succession of open grassland and meadow habitats.
Open areas need to be maintained without directly damaging plants. This can be done at the appropriate time of year after seed has been disbursed.
Find out if this plant can recover from succession by seed banking. Discover what is limiting the spread of this species since it occurs in artificial and common habitats.
The existing sites for this species in New York are mostly early successional, artificially-created habitats such as powerline right-of-ways, roadsides, and pasturelands (New York Natural Heritage Program 2007). Dry or damp sterile open soil (Fernald 1970). Dry upland woods and beaches (Gleason 1952). Dry upland woods and beaches (Gleason & Cronquist 1991).
Most New York records for this species are from Long Island, though in recent years it has been discovered in scattered locations in the Hudson and St. Lawrence Valleys, as well as in Western New York.
Southern Yellow Flax is known from all the states east of the Mississippi, excepting New Hampshire, and reaches its western limit in Texas, Oklahoma, Kansas, Iowa, and Wisconsin. In Canada it is known only from Ontario.
Southern Yellow Flax is a perennial, glabrous herb 2-7 dm tall. It has alternate (except sometimes for the lowermost 1 or 2 nodes), entire, and lance-shaped leaves up to 2.5 cm long, the upper ones pointed at the tips. The flowers are borne on stiffly-ascending branches. They have light yellow petals 4-8mm wide that are fused at the base. The inner sepals have glandular bases. The fruit are small (2 mm) dry, rounded capsules, commonly purple above (Rhoads and Klein 2002, Gleason and Cronquist 1991).
This species is best identified when fruiting.
Linum sulcatum, L. virginianum, L. striatum, and L. intercursum are the other yellow-flowered flax species found in New York. Linum sulcatum is an annual species, and its leaves have dark, stipular glands at the leaf bases (Voss 1985). L. virginianum and L. striatum differ from L. medium by having opposite leaves at several of the lower nodes, more spreading infloresences, and inner sepals which are not glandular.
Linum intercursum is similar in habit, stature and foliage to L. medium, but the fruit is ovoid with the carpels pointed at the top, and usually yellow, while L. medium is rounded with flat-topped carpels, and usually purple (Rhoads and Block 2000, Voss 1985, Gleason and Cronquist 1991).
Linum medium var. texanum flowers from mid-July to mid-August, and the fruits can persist to late November.
The time of year you would expect to find Southern Yellow Flax flowering and fruiting in New York.
Southern Yellow Flax
Linum medium var. texanum (Planch.) Fern.
Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.
Clemants, Steven and Carol Gracie. 2006. Wildflowers in the Field and Forest. A Field Guide to the Northeastern United States. Oxford University Press, New York, NY. 445 pp.
Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.
Haines, Arthur and Thomas F. Vining. 1998. Flora of Maine. A Manual for Identification of Native and Naturalized Vascular Plants of Maine.
Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.
New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.
New York Natural Heritage Program. 2019. New York Natural Heritage Program Databases. Albany, NY.
Rhoads, A.F. and T.A. Block. 2000. The Plants of Pennsylvania: An Illustrated Manual. University of Pennsylvania Press: Philadelphia, Pennsylvania. 1061 pp.
Voss, E.G. 1985. Michigan Flora. Part II. Dicots (Saururaceae - Cornaceae). Cranbrook Institute of Science and University of Michigan Herbarium. Ann Arbor, Michigan. 724 pp.
Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://newyork.plantatlas.usf.edu/, Albany, New York
Weldy, Troy W. and David Werier. 2005. New York Flora Atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research. University of South Florida]. New York Flora Association, Albany, NY. Available on the web at (http://newyork.plantatlas.usf.edu/).
Information for this guide was last updated on: December 11, 2008
Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Linum medium var. texanum. Available from: https://guides.nynhp.org/southern-yellow-flax/. Accessed March 20, 2019.