Sedum lanceolatum is a species of flowering plant in the stonecrop family known by the common names lanceleaf stonecrop and spearleaf stonecrop. It is native to western North America and occurs in western Canada and the United States. It is distributed from Alaska to Arizona and New Mexico and as far east as South Dakota and Nebraska. It grows in exposed, rocky mountainous habitats at moderate and high elevations, up to 4,048 meters (13,281 ft) in the Rocky Mountains. The plant persisted and evolved on sky islands and nunataks in these ranges during glaciation events during the Pleistocene epoch.
Description Sedum lanceolatum is a very short succulent plant. Each plant will develop numerous branching sterile stems with tight clusters of leaves. The stems are both decumbent and ascending, growing along the surface of the ground or curving to grow upwards. Each stem will have a rosette of leaves at its end. The branchlets are easily broken apart. Each stem is biennial, but replaced by offsets. The leaves are not easily detached from the stems and are attached to the stems in a spiral. The shape of the leaves is subterete, nearly circular in cross section, with an outline that can be lanceolate, elliptic-lanceolate, or elliptic-ovate. They are also quite short, just 4.2 to 13 millimeters long, and 1.5–3.5 mm in width. The leaves vary in color with those exposed to strong, full sun conditions they are maroon while in less exposed situations they are dark gray-green and dull. The flowering stems are erect, growing straight upwards, to between 3 and 18 centimeters (1.2 and 7.1 in) in height. Leaves are attached alternately to flowering stems and often fall off by the time the flowers begin to bloom. The flowering head is a flat-topped cluster of yellow flowers. The number of flowers on each stem may be as few as three or as many as twenty-five. They are either loosely or densely packed on a branched cyme, a type of determinate inflorescence.
The flowers have canary to golden yellow petals sometimes tinged with red, especially on the central rib. Each flower will usually have five petals and five sepals, but occasionally may have just four. The petals are longer than the sepals, normally measuring 6 to 9.2 millimeters long, but occasionally just 5.5 mm. They are lanceolate to ovate in shape. The ten stamens are tipped with yellow anthers. Each flower will normally produce five carpels but can occasionally have just four. The central flower will be noticeably larger than the other flowers on a stem. The plant reproduces sexually by its tiny, lightweight seeds, or vegetatively when sections of its stem break off and root. The seeds are about 1 mm in size and brown to dark brown in color. The related narrow-petaled stonecrop (Sedum stenopetalum) can be distinguished by a ridge on the underside of its leaves.
Taxonomy
Sedum lanceolatum is classified in the Sedum genus in the family Crassulaceae. The scientific description and name of the species was published in 1827 by John Torrey. There are significant genetic differences between populations of lanceleaf stonecrop between the Southern Rocky Mountains and the Central Rocky Mountains across the Wyoming Gap and what is now the Wyoming Basin shrub steppe because the lower altitudes serve as a barrier to this and other species with a preference for high elevations. Additionally, during the most recent glacial period, genetic evidence supports that the species was isolated in sky islands and nunataks that protruded above the glaciers.
Subspecies The species has two accepted subspecies, though the Flora of North America following the classification by Charles Leo Hitchcock lists them as varieties.
Sedum lanceolatum subsp. lanceolatum The autonymic subspecies is much more widespread, growing through much of the western United States and Canada. It differs from subspecies nesioticum in having shorter leaves on average, ranging from 4.2 to 9 mm where the sister subspecies is 8 to 13 mm. Its flowering stems are 5 to 15 cm (2.0 to 5.9 in) tall and its flowers have sepals that measure 2–4 mm with petals 6–9 mm. It can grow from sea level to elevations of 4,100 meters (13,500 ft).
Sedum lanceolatum subsp. nesioticum
This subspecies was scientifically described as a species and named Sedum nesioticum in 1941 by George Neville Jones. It was reclassified as a subspecies by Robert Theodore Clausen in 1948. It grows near the ocean in British Columbia, Washington, and Oregon. It is distinguished from the more widespread subspecies by having leaves that are wider, 3-3.5 mm, and at 8–13 mm longer on average with some overlap. Its flowering stems reach 10 to 30 cm (3.9 to 11.8 in) tall, also somewhat larger as are the sepals and petals, 4–5 mm and 9–9.2 mm in length respectively. It flowers two weeks later on average, likely due to the cooling effect of growing near the Pacific Ocean. Its populations are all found within 20 meters (66 ft) of sea level.
Synonyms Sedum lanceolatum has 13 synonyms of the species or one of its subspecies.
Names The species name, lanceolatum, means lanceolate. In English it is known by the common name lanceleaf stonecrop and the variant lance-leaf stonecrop. It is additionally known as spearleaf stonecrop and common stonecrop. It is at times also called yellow stonecrop, but it shares this name with Sedum acre, Sedum nuttallianum, and Sedum stenopetalum.
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