218 REV. G. HENSLOW ON THE ORIGIN OF PLANT-STRUCTURES 
The Origin of Plant-Structures by Self-Adaptation to the Envi- 
ronment, exemplified by Desert or Xerophilous Plants. By 
the Rev. Georce Henstow, M.A., F.L.S., &c. 
[Read 16th November, 1893.] 
(Prats XII.) 
ConTENTS. 
I. Introductory Observations on the Characteristic Features of Plants 
of Deserts and Arid Countries. 
IT. General Morphological Characters. 
IIT. Spinescent Characters. 
IV. Foliage of Desert Plants. 
VY. Succulent Plants. 
VI. Protection of Buds. 
VII. Roots. 
VIII. Histological Peculiarities of Desert Plants. 
IX. Assimilative Tissues. 
X. Ligneous Tissues. 
XI. Water-storage Tissues. 
XII. Secretions. 
XIII. General Summary of Observations on Desert Plants. 
XIV. Self-fertilization of the Flowers of Desert Plants. 
I. Introductory Observations on the Characteristic Features of 
Plants of Deserts and Arid Countries. 
Tue general facies of the flora of a country with a relatively dry 
soil and atmosphere is very observable ; and when it is found to 
be the same in widely separated countries—as in the desert 
regions of North Africa, in the arid districts of India and Thibet, 
of Afghanistan, in parts of Australia, in S. Africa, in Brazil*, &c.,— 
* For an interesting description of the plants growing in a very dry region 
of Brazil, but probably of less intensity than that of the African deserts, 
the reader is referred to a paper by M. Ed. Warming entitled, “ Lagoa Santa 
(Brésil), Etude de Géographie Botanique,” Rev. gén. de Bot. 1893, p. 145. 
Many peculiarities mentioned by that author correspond more or less exactly 
with those I have described in this paper. 
Grisebach also compares the 8, African region (Kalahari) with the Soudan :— 
“Les autres formes végétales sont les mémes qu’on retrouve dans d’autres 
steppes et déserts, ou bien elles signalent l’intime affinité du Kalahari et du 
Soudan. A la premiére catégorie appartiennent les plantes grasses (Euphorbia, 
Mesembryanthemum), les yégétaux bulbeux qui ouvrent rapidement leurs fleurs 
aprés les orages d’été (ex. Amaryllis); parmi les arbustes, les formes de 
Spartium (ex. Lebeckia), de /}Oléandre (par Ventremise d’une Rubiacée, le 
Vangueria), et du Myrte (par une Ebénacée, VEuclea); enfin, les arbustes & 
fouilles velues, particulidrement fréquents dans la savane (Zarchonanthus).” 
(Vég. du Globe, vol. ii. pp. 255, 256.) 
