Mentzelia decapetala, commonly known as tenpetal blazingstar, evening-star, or ten petaled western star is a biennial or short-lived perennial with large white flowers that bloom at night.

It is native to dry areas of the western Great Plains in the United States and southern Canada.

[7] The rough texture of the leaves is produced by stiff, barbed hairs which will cause them to stick quite tenaciously to clothing or fur.

[11] In its first year of growth tenpetal blazingstar has a basal rosette of leaves 10 to 20 centimeters (3.9 to 7.9 in) long and 1 to 3.5 cm (0.39 to 1.38 in) wide.

They are oblong to oblanceolate, somewhat rectangular with rounded corners or having an outline like that of a reversed spear head with the point towards the stem and the broadest part past the midpoint.

Leaves towards the ends of the stems are elliptic to lanceolate in shape, the latter like a spear head with the widest part below the midpoint.

[3] The center of the flower is filled with approximately 200 to 300 stamens,[8] white to yellow in color and strongly clawed, curving inwards.

[16] Each flower lasts many evenings, opening each night and closing for the day,[17] unless the morning is quite cloudy.

[17] They may bloom early as June or as late as August, or on occasion even into October, in its native range.

Studies of the genetics of this and other species have shown that Bartonia is a monophyletic group and it is recognized as a section of Mentzelia.

[22] Specimens of the species were collected during the Lewis and Clark Expedition in August 1804 near the Omaha village of Tonwontonga.

He had collected them along the Missouri River in 1811 and some of the seeds were planted at the garden of the Fraser Brothers at Sloane Square.

[36] Tenpetal blazingstar is native to a large part of the Great Plains from northern Texas to southern Canada from Alberta eastwards to Manitoba.

[9] It does not compete well with other plant species and for this reason is generally found in areas with less vegitation such as on shale outcrops.

[24] Tenpetal blazingstar was evaluated by the conservation organization NatureServe in 1988 and rated as secure (G5) at the global level.

[1] It is of moderate importance for the conservation of prairie ecosystems that may be introduced to appropriate habitats further north for assisting its migration in response to climate change.

[41] The moth Anoncia leucoritis feeds on the seed pods of tenpetal blazingstar as larvae and in turn is parasitized by the wasp Bracon mellitor.

[42] The bee Perdita wootonae is an oligolectic species, one that narrowly specializes in collecting pollen from very few sources.

However, when they climb out on the long stamens to collect the pollen they do not transfer any to the stigma of the flower producing no benefit to the species.

Study of the species in a greenhouse found that it will have full seed capsules even when isolated from insect pollinators.

Loose pollen released when the flower opens is deposited on the reproductive parts when the bloom closes up for the day.

[47] Due to the very long and fiberous taproot plants are difficult to transplant and are more often seeded in the desired location in a garden.