GREENFIELD: HISTOLOGY OF THE RUSSIAN THISTLE. 269 



structure similar to that of the Salsola kali var. tenuifolia is 

 compiled from Solereder's Systematic Anatomy of the Dicoty- 

 ledons (1908) : 



DlLLENIACE^. 



The anomaly is present only in the genus PoUocai'piis, and consists in 

 the formation of successive concentric rings of bundles. The secondary 

 cambium appears in the parenchjTnatous pericycle internally to the 

 primary groups of bast fibers. 



MeNISPERMACEvE. 



Anomalous stem structure occurs only in certain members of the family, 

 and in these cases a transverse section shows several concentric rings of 

 vascular bundles, which either encircle one another completely on all 

 sides of the transverse section or only develop strongly on one side. 

 These secondary arcs or rings of vascular bundles are due to the activity 

 of a cambium which arises in the innermost part of the primary cortex. 



Capparide^. 



Anomalous stem structure in the form of successive rings of growth 

 has been met with in the genera Meeriia, Roydsia, Cadaba, and Forchham- 

 meria. 



In Mierim uniflora secondary rings arise intrafascicularly in the zone of 

 bast. (DeBary, 1877.) 



In Forchhammeria trifoliata Radlk., Mxrua obloiigifoUa A. Rich., and 

 Roydsia, according to Radlkofer, they arise on the inner side of the 

 sclerenchyma of the pericycle. 



In Forchhammeria apiocarpa Radlk. and Forchhammeria pallida 

 Liebm., according to Radlkofer, they arise on the outer side of the per- 

 icyclic sclerenchyma. 



In Cadaba glandulosa the secondary rings arise in the outer primary 

 cortex, according to Kriiger (1884). 



POLYGALE^. 



Anomalous structure of the axis was first described by the older 

 authors in Seniridaca volubilis and Comesperma. According to H. Schenck 

 (1893), we must add: Bredemeyera, Schenckiana Chodat, Securidaca 

 lanceolata St. Hil., and Seciiridaca sellowniana, and, according to Chodat, 

 Moutabea guianensis. The formation of the secondary bundles, accord- 

 ing to H. Schenck, takes place in the parenchymatous pericycle on the 

 inner side of the bundles of primary hard bast. 



Caryophyllace^. 

 Successive rings of bundles appear in the root and stem of Spergularia 

 and species of Polycarpiea. Secondary rings of growth have been observed 

 by Morot in the root of Lepigonum marimim, by Peterson in the root of 

 Lipigonum salinum, by H. Schenck in the root and stem of Spergularia 

 media Presl. and by Solereder in the root of Polycarpia fragilis Del., and 

 P. corymbosa Lam. They arise extrafascicularly. 



2-Univ. Sci. Bull.. Vol. VII. No. 16. 



