Common names:
Silver senna, wormwood senna
Scientific name:
Senna artemisioides
Range:
South California, south and central Arizona (non-native)
Habitat:
Roadsides, disturbed ground, washes, rocky slopes
Leaves:
Pinnate, with 6 to 16 narrow, linear, grey-green leaflets, up to 1 inch long and less than 0.1 inches wide
Senna artemisioides is an Australian species, naturalized in and around various towns in southern Arizona and southern California. Plants are shrubs, up to 6 feet tall, profusely branched and sparsely hairy. Leaves, attached by stalks of around half an inch, are divided into three to eight pairs of well-separated linear leaflets, very narrow, with prominent midveins. The lower few leaflet pairs have one or more yellowish glands below the attachment point.
Flowers are formed of five hairy, greenish-yellow sepals, five much larger hairless, orange-yellow petals, and ten stamens, of unequal lengths, with thick yellowish filaments and relatively large, elongated brownish anthers. Fruits are flat green pods, up to 3 inches long.