Volume 22, Issue 4
October 1945, pages 219-256
pp 219-224 October 1945
The present is a preliminary report about the age of cotton leaves preferred for oviposition byEmpoasca devastons. It has been shown that the insect prefers leaves of about 35 to 45 days age. The younger and the older leaves are usually left alone.
This finding is very important in breeding varieties for jassid resistance as the Worker must look for the “jassid effect” in the middle zone of the plant rather than at the top or the bottom.
pp 225-231 October 1945
The embryology ofAlangium Lamarckii Thw. has been studied. A cross-section of the anther shows an epidermis, the endothecium, a single middle layer and the tapetum. The haploid number of chromosomes is eight. There is a single anatropous ovule with one integument. The development of the embryo-sac conforms to the Normal type and an epithelial layer is formed from the inner epidermis of the integument. Fertilization is porogamous and the endosperm nuclear. It is concluded that the genusAlangium should be placed in a separate family, the Alangiaceæ, under the order Umbellifloræ.
pp 232-256 October 1945
The genusQuercus is abundantly represented in Karewa flora by five well determined species, namely,Q. dilatata, Q. semecarpifolia, Q. Ilex,Q. incana andQ. glauca which form the greater part of the material collected by Middlemiss, de Terra, Sahni, Stewart and the author from the Lower Karewa lake deposits of the Pleistocene age exposed at Liddarmarg, Gogajipathri, Dangarpur, Laredura and Botapathri.
The oaks, which must have been dominant trees in the flora of the Kashmir Valley during the Pleistocene, are unrepresented in the modern vegetation of the valley and of the mountain slopes flanking it to the northeast and south-west. Three of the fossil species, namely,Q. semecarpifolia,Q. dilatata andQ. incana are at present very common in the outer ranges of the western temperate Himalayas, often forming pure forests or occurring with conifers, or broad-leaved trees in the well-defined elevation zones which succeed each other from the higher to the lower altitudes in the above order. Regions with heavy monsoonic rainfall and moderate snowfall (Quercus semecarpifolia reaches the upper limit of the tree growth) are congenial for their growth.Quercus Ilex is confined to the inner dry ranges of the Himalayas, whereasQuercus glauca occurs in the outer ranges at lower elevations.
The modern distribution of the five species is given in some detail and their present associates (conifers and broad-leaved genera) in different types of forests in the Himalayas are mentioned.
The significance of the occurrence of the oaks in the Kashmir Valley during the Pleistocene is discussed and it is concluded that the valley, at a time when the oak forests were flourishing on the northern slopes of the Pir Panjal Range must have had a tropical climate unlike the temperate conditions of the present day.
The abundance of oak leaves in these deposits supports the universally accepted theory of the Pleistocene uplift of the Himalayas.