132 Trans. Acad. Sci. of St. Louis. 



it is spherical with a slender prolongation below and a slender 

 crown above. Asclepias stenophylla, Polytaenia Nuttallii 

 and others have a slender fleshy root. The first has a rhizome- 

 like crown and the other is surmounted by a caudex. Some- 

 times the crown branches and there are several small crowns 

 tracing back to the same root. In several cases, Lithosper- 

 mum hirtum, Astragalus caryocarpus, and Petalostemon, the 

 root is thick and woody rather than fleshy, while the top 

 forms a compact crown. 



In the second series, the simplest case is that of a small 

 tap-root extending upward into a single vegetative stem the 

 first year. The second season vegetative shoots arise from 

 buds at the base of this stem. If the plant is long lived the 

 crown thus formed becomes thicker and thicker from year to 

 year. Verbena and N^epeta Calaria are examples. If a mass 

 of fibrous roots is produced instead of a tap-root a crown 

 of a different nature is produced. In most cases the older 

 portion below dies off and the crown is thus relatively small. 

 Examples are Ruellia ciliosa and Asclepias incarnata. The 

 base of the vegetative stem may be oblique or decumbent, in 

 which case the new stems often appear as offsets along the 

 base and become independent at an early date, as Pentstemon 

 Cobaea. In Penthorum sedoides autumn rosettes are pro- 

 duced which elongate the following spring. There is a 

 transition from such oblique offsets to short rhizomes. 



Propagation by Stolons. Here are included those species 

 which propagate by means of stems above ground rooting 

 and thus forming independent plants. Symplioiicarpos 

 vulgaris forms prostrate leafy branches for this purpose while 

 Fragaria Virginiana forms the familiar runners and Rubus 

 occidentalis roots at the tips of the recurved branches. 



Propagation by Rhizomes. There are all gradations from 

 the oblique branches from a crown to the extensive rhizomes 

 of Rumex venosus and Laportea Canadensis. The upright 

 rhizome or caudex has been mentioned as occurring at the 

 summit of a fleshy root. Often it is the chief underground 

 portion, bearing lateral fibrous roots. There is a transition 

 from the vertical caudex through the oblique caudex to the 

 slowly creeping horizontal rhizome such as TJialictrum pur- 



