- Scientific name: Linum medium var. texanum (Planch.) Fernald
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
- Threatened (MA Endangered Species Act)
Description
Stiff yellow flax, Linum medium var. texanum, is a perennial herb of the flax family (Linaceae), with yellow five-petalled flowers borne on stiff, ascending branches. Plants grow 2 to 7 dm (~8–28 in) in height. The flower petals are 4-8 mm (0.16–0.31 in) long. The styles are distinct (i.e., not united at the base). The sepals are imbricate, and the inner ones have teeth with bulbous glandular tips along their edges. Leaves are entire, lance-shaped, and up to 2.5 cm (1 in) long with the largest leaves towards the base of the plant. The upper leaves are alternate and usually have pointed tips, while those of the lowest nodes are opposite and blunt tipped. The sepals persist long after the petals have withered and subtend the small (2 mm; 0.08 in), dry seed capsules. The species is most often found growing in barren, disturbed areas on sterile soil.
AIDS TO IDENTIFICATION:
- Plants with stiffly ascending branches
- Densely leaved with 30 to 70 leaves below the inflorescence
- Lowest leaves opposite; upper leaves alternate
- Seed capsules more-or-less spherical with a flattened top
- Inner sepals with glandular teeth
- Most easily identified when fruit are present
Four yellow-flowered Linum species that might be mistaken for stiff yellow flax occur in Massachusetts. Grooved yellow flax (L. sulcatum var. sulcatum) differs from the other three in that it is an annual and its styles are united at the base. Woodland yellow flax (L. virginianum) and panicled yellow flax (L. striatum) differ from stiff yellow flax in having more spreading branches and sepals lacking glandular teeth. Sandplain flax (Linum intercursum) is very similar in form to stiff yellow flax but the fruit capsule is egg-shaped with a pointed top, rather than spherical with a flattened top, as in stiff yellow flax.
Life cycle and behavior
This is a perennial species.
Population status
Stiff yellow flax is listed under the Massachusetts Endangered Species Act as Threatened. All listed species are protected from killing, collecting, possessing, or sale and from activities that would destroy habitat and thus directly or indirectly cause mortality or disrupt critical behaviors. There are 9 populations of stiff yellow flax that have been verified since 1999 in Barnstable, Bristol, Dukes and Plymouth Counties. Historically it also occurred in Berkshire, Middlesex, Norfolk and Suffolk Counties.
Distribution and abundance
Stiff yellow flax occurs in all the states east of the Mississippi River except New Hampshire. The western limit of its range extends from Texas and Oklahoma, north to Iowa, and Wisconsin. In Canada it is known only from Ontario.
Distribution in Massachusetts. 2000-2025. Based on records in the Natural Heritage Database.
Habitat
In New England, this species typically inhabits sparsely vegetated mineral soils of clearings, fields, roadsides, and rights-of-way; soil moisture ranges from very dry to wet or seasonally flooded. Most documented stiff yellow flax habitats in the state have been created or maintained via anthropogenic disturbance (e.g., utility right-of-way). Associated plant species include broom-sedge bluestem (Andropogon virginicus), slender-leaved flat-topped goldenrod (Euthamia caroliniana), switch-grass (Panicum virgatum), long-leaved panic-grass (Coleataenia longifolia ssp. longifolia; threatened), forked panic-grass (Dichanthelium dichotomum), Philadelphia panic-grass (Panicum philadelphicum ssp. philadelphicum; Special Concern), yellow wild indigo (Baptisia tinctoria), large cranberry (Vaccinium macrocarpon), and brown beak-sedge (Rhynchospora capitellata).
Healthy habitats are vital for supporting native wildlife and plants. Explore habitats and learn about conservation and restoration in Massachusetts.
Threats
Invasive species are the primary threat to stiff yellow flax.
Conservation
Stiff yellow flax requires periodic disturbance to reduce competition and shading by woody plants, and possibly to expose mineral soil for improved germination and seedling establishment. Currently, stiff yellow flax in Massachusetts is dependent upon anthropogenic disturbance such as mowing, cutting, and herbicide application for habitat creation and maintenance; however, wildfire may have once filled this role and, when possible, prescribed burning might be the best management tool. To avoid disruption of flowering and fruiting, vegetation control in stiff yellow flax habitat should be conducted in early spring or late autumn. Management in areas adjacent to occupied sites could be effective in encouraging population expansion. Exotic plants known to invade dry, disturbed habitats, such as knapweeds (Centaurea spp.) are capable of dominating vegetation cover once they become established; therefore, sites should be monitored for exotic plant invasions and if necessary a plan for control should be constructed. Additional threats include destructive habitat disturbance that damages plants or compacts soil, such as use of off-highway vehicles; such recreational access of habitat sites should be restricted. All active management of state-listed plant populations (including invasive species removal) is subject to review under the Massachusetts Endangered Species Act and should be planned in close consultation with the MassWildlife’s Natural Heritage & Endangered Species Program.
References
Gleason, Henry A., and Arthur Cronquist. Manual of Vascular Plants of Northeastern United States
and Adjacent Canada, Second Edition. Bronx, NY: The New York Botanical Garden, 1991.
Haines, A. 2011. Flora Novae Angliae – a Manual for the Identification of Native and Naturalized Higher Vascular Plants of New England. New England Wildflower Society, Yale Univ. Press, New Haven, CT.
NatureServe. 2025. NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. Accessed: 5/23/2025.
New York Natural Heritage Program. 1999. Conservation Guide for Southern Yellow Flax (Linum medium var. texanum). NYNHP, Albany, NY.
POWO (2025). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; https://powo.science.kew.org/ Accessed: 5/24/2025.
Contact
| Date published: | April 30, 2025 |
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