4 Trans. Acad. Set. of St. Louis. 



terminate in a flowerinor shoot I have not ascertained. An 

 examination of the internal structure of this rhizome shows 

 that below an indefinite corky layer is a layer of stone cells 

 (three or four cells thick). These stone cells are about three 

 times as long as wide, with very much reduced cavity. There 

 are no strands of sclerenchyma. The central portion of the 

 rhizome contains large quantities of inulin. Artemisia dra- 

 cunculoides forms a large woody crown similar to shrubs, 

 consisting of stems upon a woody branched root. 



Of the crown forming species mentioned, Vernonia fasci- 

 cidata, V. Baldwinii (transition to xerophyte), Eupatorium 

 perfoliatum, E . ageratoides. Aster Drummondii, Acti7wmeris , 

 Chrysanthemum, Taraxacum are mesophytes, though some 

 are found more or less frequently in xerophyte communities. 

 All the others are xerophytes growing on prairie and lime- 

 stone hills. A few prefer limestone hills, such as Echinacea^ 

 Troximon and Hymenopappuf^ . 



Propagation by stolons. The only examples of this are our 

 two Antennarias, A. planiaginifolia and A. campestris. The 

 former grows in dry open woods and the latter is common on 

 the prairie. Slender stolons are sent out just above the sur- 

 face. These end in rosettes which form new plants. If the 

 stolons are short they would be called offsets. 



Propagation by rhizomes. As was said in a preceding 

 paragraph there is a transition from the formation of a loose 

 crown of intertwined stem bases to the production of short 

 rhizomes, as in Helianthus Maximiliani. In Helianthus 

 tuberosus tubers are formed at the ends of the rhizomes. 

 Achillea Millefolium forms summer rhizomes, each producing 

 a rosette of leaves. The following are mesophytes grow- 

 ing in moderately moist soil: Solidago serotina, S. Cana- 

 densis, jS. Lindheimeriana, S. lanceolata. Aster panicu- 

 latus, Helianthus grosse-serratus, H. tuberosus, IT. hirsutus. 

 The others are xerophytes. Solidago Missouriensis, Aster 

 oblongifolius rigidulus, A. muUiflorus, Helianthus rigidus, 

 Achillea Millefolium and Artemisia Ludoviciana prefer prai- 

 rie, w^hile Helianthus Maximiliani prefers limestone bluffs. 

 The latter is the only rhizome forming species which is at all 

 common in stony soil and as was said the rhizomes are so 



