Xanthisma spinulosum (Cutleaf Ironplant)
|Also known as:||Lacy Tansyaster, Spiny Goldenaster|
|Habitat:||sun; dry prairie|
|Bloom season:||June - September|
|Plant height:||4 to 20 inches|
|Wetland Indicator Status:||none|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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1 to 10 stalked, daisy-type flowers at the tips of branching stems. Flowers are about 1 inch across, with 14 to 60 yellow petals (ray flowers) and a small, yellow center disk.
The bracts (phyllaries) surrounding the base of the flower are overlapping in 5 or 6 layers; bracts are lance-linear, pointed at the tip with a white bristle at the apex, variously covered in matted woolly hairs, sometimes hairless, and sometimes also glandular-hairy.
Leaves and stems:
Leaves are numerous, alternate, spreading to ascending, ½ to about 1 inch long, deeply divided into narrow segments, the lobes lance-linear to triangular, sometimes further lobed or with a few teeth, and each lobe with a white bristle at the tip. Surfaces are variously hairy, from hairless or nearly so to densely covered in matted woolly hairs, the leaf color correspondingly green to gray-green. Leaves may also be glandular-hairy.
Stems are branched, green, sparsely to densely covered in matted woolly hairs. Depending on the variety, stems may be erect, branched on the upper stem and woody at the base, or speading to sprawling with branching on the lower stem and not woody at the base.
The center disk becomes a head of dry, hairy seeds with tufts of light brown hairs to carry them off in the wind.
Cutleaf Ironplant, formerly known as Haplopappus spinulosus, Sideranthus spinulosus or Machaeranthera pinnatifida, is a dry prairie species that reaches the eastern fringe of its range in Minnesota. It is a variable species with as many as 7 varieties, most of which are restricted to the southwest, and based primarily on leaf and stem characteristics, including: whether it has a woody base, stems erect or more sprawling, branched on the lower stem or not, leaf size, shape and distribution, leaves mostly spreading or all ascending, degree of hairiness and toothiness, glandular hairy or not. According to the DNR, fewer than 20 locations are known in Minnesota, and those populations are all small. It was listed as a Special Concern species in 1984, mostly due to loss of prairie habitat. While the yellow flowers resemble those of the common Goldenaster (Heterotheca villosa), Cutleaf Ironplant is easily distinguished by the divided leaves with bristle-tipped lobes and the bristle-tipped phyllaries.
The DNR lists var. spinulosum present in Minnesota, but a 2007 taxonomic review by Nesom and Turner in Texas suggests we actually have var. glaberrimum here instead, with var. spinulosum ranging from Montana south and barely reaching into the Dakotas. Per the 2007 review and the description from Flora of North America, var. spinulosum stems are usually spreading to sprawling, rarely woody at the base, branched on the lower half or so, leaves spreading to ascending, slightly to densely woolly hairy, and usually glandular. By contrast, var. glaberrimum stems are stiffly erect, often woody at the base, unbranched except in the upper third, leaves all ascending, hairless or slightly woolly hairy, and usually not glandular. Our images (all from North Dakota) possibly represent both vars but we can't say for certain. We have not seen Minnesota populations ourselves and will have to see how this turns out, but in the meantime we're following the 2007 taxonomy.
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- Cutleaf Ironplant
- Cutleaf Ironplant, spreading stem branched below
- Cutleaf Ironplant, erect stem branched above
- Cutleaf Ironplant habitat, with Dotted Blazingstar
Photos by K. Chayka taken at Cross Ranch, North Dakota. Photos courtesy Peter M. Dziuk taken at Cross Ranch and near Garrison in North Dakota.
Have you seen this plant in Minnesota, or have any other comments about it?