MORPHOLOGY, GENETICS AND BREEDING 59 



Kurtz (41) in 1875, failed to discover Bentham's retraction and criti- 

 cized him severel}'. Other writers have overlooked Bentham's (11) cor- 

 rection of his mistake, and one may find his erroneous concept in many 

 recent reference works and texts which Smith (66) has cited. The read- 

 ers of these usually reliable works of the past 40 years will do well to be- 

 ware while perusing the section dealing with Arachis hypogaea. 



VARIABILITY, GENETICS AND BREEDING 

 Variability 



In the preceding pages of this chapter we have described in general 

 terms the form, structure, and reproductive morphology of peanuts. On 

 occasion we have given ranges of size, number, and kinds of some of the 

 things described. It should be borne in mind, however, that the detailed 

 studies necessary to the descriptive morphology of a plant cannot pos- 

 sibly characterize all the plants in a genus, a species, or even a single va- 

 riety. It is the common possession of certain basic features, however, 

 which leads to the establishment of such taxonomic entities. The confi- 

 dence with which we place a group of plants in a single taxonomic cate- 

 gory is based on no more than a conceived average of the almost universal 

 variability found in any natural group. It is the discovery that this range 

 of variation extends beyond the accepted but sometimes ill-defined limits 

 which leads to the creation of new varieties, species, genera, or higher 

 taxonomic categories. 



The systematic position of the genus Arachis was for a long time a 

 moot question. In 1839 Bentham ( 10) first properly associated Arachis 

 with Stylosanthes and Chapmannia in the tribe Hedysareae. Taubert (70) 

 separated the tribe Hedysareae (which includes such plants as beggar's 

 ticks and lespedeza) into six subtribes; the last of these, the Stylos- 

 anthineae, includes the peanut and its relatives. This subtribe includes 

 only four genera, Zornia, Chapmannia, Stylosanthes, and Arachis. They 

 possess in common the following features : 



"Stamens all united into a closed tube; anthers alternately basally* 

 and dorsally attached; flowers in terminal or axillary spikes or small 

 heads, seldom somewhat raceme-like; leaves pinnate, mostly with few 

 leaflets, without stipels." (Taubert, 70. Translated from the German). 

 Arachis, Stylosanthes, and Chapmannia form a closely related group, all 

 of them possessing the characteristic tubular hypanthium, pinnate leaves, 

 and straight embryo. Zornia dififers materially from the rest of the tribe 



* Adnate, introrse in Arachis— author's note. 



