Pluchea sericea aka Arrow Weed

Pluchea sericea is an evergreen shrub in the aster family, Asteraceae. It grows wild in the southwestern and south-central United States. Its native range also reaches into Mexico. This includes Baja California and Sonora. Kew places it in desert or dry shrubland. That broad habitat does not tell gardeners when to water. Its woody shape and lasting leaves give it year-round form. Virginia Tech calls it a dense shrub that forms thickets. Its stems often grow straight, in close groups of upright shoots.

The shrub grows about 10 feet [3 metres] tall. The sources give no width for a full-grown plant. Its bark changes in both shade and feel with age. Young bark may be smooth or have lenticels. These are small marks or pores in the bark. Old bark turns rough, with grey to brown tones. Young twigs are thin and grey-green, with fine, pale hairs. As the twigs age, they turn grey-brown. This sets young growth apart from the older woody stems.

The leaves grow in an alternate pattern along the stems. Each leaf is simple, not split into leaflets. The blades range from narrow and linear to lance-shaped. Their edges are entire: they have no teeth or lobes. Leaves reach about 0.21 feet [0.064 metres] in length. Both sides are grey-green and have fine hairs. These hairs give each side a soft look. The leaves stay green year-round. They do not form a deciduous crown that sheds its leaves. Their slim shape contrasts with the shrub's dense thickets.

Purple flowers grow in groups at the ends of twigs. They bloom from spring to the middle of summer. Small fruits called achenes then form. Each fruit has thin brown bristles. These fruits look quite unlike fleshy berries or large pods. The sources give no needs for garden soil or light. They do not state how much cold it can bear. Nor do they give a supported account of pests or diseases. They give no food use or findings on toxicity. Its desert range alone does not show that use is safe. Nor does that range show its exact care needs. The supplied sources leave these points unconfirmed.