^<a>i*"* ^' 



Volume 13 ^- Number 2 



The Plant World 



A Magazine of General Botany 

 FEBRUARY, 1910 



'TERATOLOGY IN JUGLANS CALIFORNICA WATS. 

 By Ernest B. Babcock. 



It is the purpose of this paper (1) to record the occurrence 

 of abnormal flowers, fruits and leaves in Juglans calif arnica 

 Wats., (2) to point out their probable significance in explaining 

 the origin of certain anomalous forms of Juglans. 



The normal blooming period of most wild trees of black 

 walnut in southern California is in April. The staminate catkins 

 appear first, being produced on the growth of the previous season. 

 They are three to five inches long when fully grown and each 

 catkin bears a large number of flowers. The pistillate catkins 

 appear about the first of April, being terminal upon the new 

 growth. They are one or two inches long and bear one to five 

 flowers so that when the nuts mature they often hang in 

 clusters (Fig. l,a). Normal pistillate flowers are bisymmetrical. 



I\Iany trees throw out lateral branchlets from the first growth 

 of the season. It is during this second period of growth, in May 

 or early June, that the teratological flowers and leaves appear 

 on certain trees. The abnormal flowers are usually produced 

 upon catkins that resemble normal staminate catkins in num- 

 ber and arrangement of the flowers, although only two to three 

 and one-half inches long. But the flowers are either pistillate 

 or bisexual, or both, no purely staminate flowers having been 

 found except in occasional catkins, which were entirely stam- 

 inate. These abnormal late catkins usually occur on the second 

 growth, lateral branchlets, one catkin in the axil of a leaf, but 

 they sometimes develop alongside the norm.al, terminal, pistil- 

 late catkin as shown in figure 2. In Brea Canyon (Puente Hills) 

 a hundred or more wild trees were examined during the season of 



