黄翠雀花

Delphinium luteum is presently known from only three populations. It is known to hybridize with D . decorum and with D . nudicaule . Populations of D . hesperium subsp. hesperium also occur at the type locality; D . luteum flowers earlier and hybrids are not known.

Delphinium luteum is not likely to be mistaken for any other species of Delphinium . It has been treated as a variety of D . nudicaule and is closely related to that species. Sepals of the infrequent yellow-flowered phase of D . nudicaule , however, have a much drabber appearance compared with the bright shining yellow of the sepals in D . luteum .

Stems 20-40(-55) cm; base often reddish, nearly glabrous. Leaves mostly on proximal 1/4 of stem; basal leaves 4-9 at anthesis; cauline leaves 2-4 at anthesis; petiole 0.5-6 cm. Leaf blade round to pentagonal, 1-5 × 2-10 cm, nearly glabrous; ultimate lobes 3-5, width 8-30 mm (basal), 5-15 mm (cauline). Inflorescences 5-25(-37)-flowered; pedicel (1-)3-5(-7) cm, puberulent; bracteoles 6-10(-17) mm from flowers, green, linear-lanceolate, 6-7 mm, nearly glabrous. Flowers: sepals bright yellow, puberulent, appearing waxy, lateral sepals ± forward pointing, (11-)14-16 × (6-)9-13 mm, spur straight, ca. 30° below horizontal, 11-20 mm; lower petal blades elevated, exposing stamens, 3-4 mm, clefts 0.5-1.5 mm; hairs sparse or absent, ± evenly distributed if present, white to yellow. Fruits 11-14 mm, 3.5-4.5 times longer than wide, glabrous. Seeds unwinged; seed coat cell surfaces smooth.

Calif.

Flowering late winter-mid spring.

Wet cliffs, coastal grassland or chaparral; of conservation concern; 0-50m.

Delphinium luteum, known by the common name yellow larkspur, is a species of small perennial herb in the buttercup family bearing bright yellow cornucopia-shaped flowers. Endemic to the rocky, foggy hillsides of coastal Sonoma County, California, it is critically endangered, with about 200 individuals believed to be in existence as of 2005.

The plant was never distributed beyond the coastal area of Sonoma and Marin counties, and has never been abundant. Activities in the area including quarrying, grazing, agriculture, and development further reduced the population of yellow larkspur to its current near-extinction. It has been listed as an endangered species since the 1970s. Extremely isolated patches of the plant still exist on private property near Bodega Bay, where it is protected.

Yellow larkspur is pollinated by hummingbirds and insects, and often hybridizes with two other Delphinium species if it receives their pollen. However, pure unhybridized individuals of yellow larkspur exist and the genetic diversity within the species is high. Recent conservation attempts have focused on specifically preserving yellow larkspur's genetic identity. A closely related flower native to the same region, Baker's larkspur, is also critically endangered, and the two species are often studied together.