242 



Descriptive Flora 



soft capillary bristles. In sand. March and April. Differs 

 from the other Senecios in having undivided leaves. 



Cirsium austrinum (Small) Thistle. "Cardo Santo" 



(Carduus austrinus Small. 



Tall, prickly plants, 1 to 3 feet high, with woolly stems 

 branching above and bearing large, solitary, rose-purple flowers. 

 Leaves simple, alternate. Blades green above, white-woolly be- 

 neath, lobed or wavy-segmented, the segments prickly toothed, 

 felted with whitish-cobwebby hairs beneath. Flowers composite, 

 rose-purple or real purple to phlox purple, about iy± across, 

 set in a cup of small, prickly-tipped bracts and singly terminat- 

 ing long, almost leafless, woolly or cobwebby flower stalks. 

 Flower consists of all tubular corollas, each having 5 deep, nar- 

 row lobes. Eay flowers none. As the seeds ripen, the flower be- 

 comes a big ball of fluffy white or greyish silk. Individual seeds 

 small, crowned by a tuft of silky plumose hairs. Grows singly or 

 in large patches along railroad tracks, roadsides and in pastures. 

 April to June. Very common. 



Cirsium undulatum (Nutt) Spreng. 



This thistle is similar to Cirsium, austrinus but the plant 

 does not grow as tall (1 to 2 feet), comes into blossom later, has 

 stouter stems, thicker leaves that are felty underneath, and much 

 larger, heavier flowers. Involucre varies from 3-4 cm in height. 

 Bracts are broader and tipped with stout spines. Flower is fully 

 twice as broad across the top as Cirsium austrinum. Plants grow 

 in dry, stony soil. May to July. Comparatively rare. 



Centaur 'ea americana Nutt. Star Thistle. i ' Cardo del Valle ' 



Powder Puffs. 



Erect, stout-stemmed plants with the tips of the ascending 

 branches enlarged into a large, showy, white or lavender thistle 

 like blossom, 2 to 4 inches across. Leaves simple, alternate. 

 Blades gland-dotted, lanceolate, entire, 1 to 3 inches long. 

 Flowers composite, composed of white tubular disk corollas and 



