STRL'CTUUE OF THK FORMATION 8.3 



iudividuals to the quadrat with an average of 18 (subcop. 1) . 

 The short spikes of bright purple flowers render the plant 

 prominent in the late floral aspect. Dissemination is by 

 means of the plumose pappus. Solidaffo rupestris frequents 

 low prairies and especially slopes ; it is found to some extent 

 in xerophilous situations. The individuals of this species, 

 in the various quadrats examined, range from 2-275, with 

 an average of 45. The plants are copio-gregarious in the 

 lower prairies, frequently forming patches 1-3 meters in 

 extent, while in the more xerophilous situations they are 

 often loosely dispersed throughout. 8. rupestris forms rather 

 open rosettes, which tend toward the closed type; it is also 

 a rootstalk plant, which partially explains its gregarious 

 habit. S. rupestris is among the earliest of the goldenrods 

 to blossom and the only estival one in the formation. Its 

 bright yellow flower clusters, especially when aggregated, 

 are among the more conspicuous objects of the aspect. The 

 achenes are modified for wind dissemination. Linum sul- 

 catum is a small, slender annual occurring frequently but 

 sparsely throughout the prairie, its average for sixteen quad- 

 rats for all conditions being five individuals. It is interesting 

 to note that in quadrats XXI and XXII (see map) both 

 with northern exposures, Linum averages 40 individuals, 

 (subcop. 1). The bright yellow ephemeral corollas open at 

 4 :00 A.M., and fall ofE between 10 :00 and 11 :00 a.m. Dis- 

 semination results from the capsules splitting open from 

 above when dry, thus scattering the seeds. 



Hieracium longipilum is a sparse or subcopious perennial 

 of low prairies. The plant is not abundant enough to be of 

 importance to the covering. Hieracium forms rather close 

 rosettes, the leaves of which are densely covered with brown- 

 ish, bristly hairs 1-2 cm. long. Silphium laciniatum is a 

 tall, coarse perennial growing sparsely in low prairies and 

 to some extent on the crest of Great ridge. It is a promi- 

 nent feature of the formation on account of its extreme size 

 (2 meters) and the large, yellow flowers. Its laciniate leaves 



