Clasping-Leaved Cone-Flower (Dracopis amplexicaulis) makes a showy display in roadside ditches from Central Texas to Louisiana and Missouri. It is a handsome plant with smooth branched stems one to two feet high. The slightly drooping rays commonly have brown spots at the base but may be all yellow. It is often called niggerhead or black-eyed Susan, but it may be distinguished from the latter by the thimble-shaped heads, which are green before the brownish disk flowers open. In South Texas it is at its best the latter part of April, but in North Texas June is its best month.
Black-Eyed Susan (Rudbeckia hirta) is a common daisy of the plains region from Southern Canada to Texas and Florida. It is a rough, hairy plant which grows from one to three feet high. Closely resembling it is Rudbeckia bicolor, which has shorter ray flowers marked with a reddish-brown base. The ray flowers of Rudbeckia hirta may also show a dark base. Both are widely cultivated. The group was named in honor of Claus Rudbeck, a Swedish botanist.
SAMPSON’S ROOT. PURPLE CONE-FLOWER
Sampson’s Root. Narrow-Leaved Purple Cone-Flower (Echinachea angustifolia) is easily recognized by the spreading or somewhat drooping rose-colored rays. The heads terminate the stiff, unbranched stems which, like the narrow leaves, are very rough and bristly. The stems grow one to two feet high and are scattered on limestone hillsides but may occasionally be found in dense patches along the roadsides. The leaves have three prominent nerves.
The scientific name is derived from the Greek and refers to the stiff reddish-brown chaff on the flower head. This chaff obscures the brown disk flowers and remains on the heads long after the seeds have fallen. This plant is hard to distinguish from the pale purple cone-flower (Echinachea pallida), which grows in the woods in the eastern part of the state. The latter has longer and more drooping ray flowers. The purple cone-flowers are well known in cultivation.
RAGWEED. LYRE-LEAVED PARTHENIUM
Ragweed. Lyre-Leaved Parthenium (Parthenium lyratum) blooms from early spring until fall in Southwest Texas. This is a smaller plant than the common parthenium (Parthenium hysterophorus), which is widespread in the Gulf States and tropical America. The latter is a widely branched plant two to three feet high and grows in dense masses. They have similar flower clusters with small heads of greenish-white flowers. Neither of these is the ragweed or bloodweed commonly associated with hay fever; however, the common parthenium is listed as a poisonous plant. Wild quinine or feverfew (Parthenium integrifolium), used as a pioneer drug to relieve fever, has been reported from the state.
Several shrubby partheniums are found in West Texas. The most important member of the group is the silver-leaved guayule or rubber plant (Parthenium argentatum), found in West Texas and Mexico. It is a commercial source of rubber but is not yet profitable, as the plants are of slow growth.