''Horkelia hendersonii'' is a rare species of flowering plant in the

rose family Rosaceae (), the rose family, is a medium-sized family of flowering plants that includes 4,828 known species in 91 genera. The name is derived from the type genus ''Rosa''. Among the most species-rich genera are ''Alchemilla'' (270), ''Sorbus' ...

known by the common name Henderson's horkelia. It is known from four populations in southern

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

, including

Mount Ashland Mount Ashland is the highest peak in the Siskiyou Mountains of southern Oregon. It was named for the city of Ashland, located north of the mountain. The Siskiyou Mountains are a subrange of the Klamath Mountains in northwestern California and ...

, and one population south of the border in

Siskiyou County, California Siskiyou County (, ) is a county in the northernmost part of the U.S. state of California. As of the 2020 census, the population was 44,076. Its county seat is Yreka and its highest point is Mount Shasta. It falls within the Cascadia bioregion ...

.Federal Register Vol 68, No 26
February 7, 2003. It is a resident of dry forest habitat in the

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

soils of the

Klamath Mountains The Klamath Mountains are a rugged and lightly populated mountain range in northwestern California and southwestern Oregon in the western United States. As a mountain system within both the greater Pacific Coast Ranges and the California Coast R ...

. This is a perennial herb producing a low mat of hairy, glandular gray-green foliage about a woody base. The leaves are cylindrical and sometimes tapering to a point, growing erect in a patch around the

caudex A caudex (plural: caudices) of a plant is a stem, but the term is also used to mean a rootstock and particularly a basal stem structure from which new growth arises.pages 456 and 695 In the strict sense of the term, meaning a stem, "caudex" is m ...

. Each leaf is 3 to 8 centimeters long and is made up of densely spaced pairs of minutely toothed leaflets. The leaflets are coated in silky hairs. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

is a dense array flowers atop an erect stalk, each flower made up of five hairy, pointed

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined b ...

s and five smaller, more delicate white petals. Although few populations of the plant are known to exist, they are not in imminent danger of destruction and a federal listing as an endangered or threatened species was declined in 2003. The Mount Ashland populations of this plant are sometimes threatened by recreational activities at that site, including

skiing Skiing is the use of skis to glide on snow. Variations of purpose include basic transport, a recreational activity, or a competitive winter sport. Many types of competitive skiing events are recognized by the International Olympic Committee (IO ...

and maintenance of ski facilities, and

off-road vehicle An off-road vehicle, sometimes referred to as an overland or adventure vehicle, is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with dee ...

use.

References

External links

Jepson Manual TreatmentPhoto gallery
hendersonii Flora of California Flora of Oregon Plants described in 1887 {{rosoideae-stub