Transpiration in Succulent Plants. 
BY 
E. MARION DELF. 
With one Figure in the Text. 
Contents. 
PAGE 
PAGE 
PRODUCTION .... 
409 
(6) Glands 
422 
Transpiration in Relation 
TO 
(7) Capacity for Superficial Absorption 
4 2 3 
Structure .... 
. 
4IO 
()S) Water-storing System . 
4 2 5 
(a) Transpiring Surface 
. 
4IO 
(1) Distribution of Water-storing 
(1) Reduction in Leaf Surface . 
. 
4IO 
Tissues ..... 
425 
(2) Transpiring Surface in Relation 
(2) Acidity or Salinity of the Cell-sap 
425 
to Succulence 
4IO 
(3) Nature of Cell-sap and the Succu- 
(3) Protective Means : 
lent Habit .... 
426 
1. Cuticle 
. 
412 
(4) Conservation of the Water Supply 
428 
2. Wax 
. 
415 
(7) The Conducting System 
433 
3. Hairs 
415 
II. Transpiration in Relation to 
(4) Stomata : 
Habitat 
435 
1. Distribution 
416 
(1) In Desert Plants . 
435 
2. Power of Regulation 
of 
(2) In Plants of Warm, Damp, 
Transpiration 
. 
417 
Tropical Regions, as in Man- 
3. Protective Adaptations 
420 
groves and Epiphytes . 
436 
(5) Aqueous Tissue : 
(3) Halophytes .... 
437 
1. Nature and Function 
42O 
(4) Halophytic and Alpine plants 
438 
2. Occurrence 
4 2I | 
III. Summary 
440 
Introduction. 
S UCCULENT plants are largely characteristic of dry, sandy, or rocky 
regions, where the physical conditions seem to favour rapid transpira- 
tion, whilst the water supply is limited, or in some way precarious. They are, 
however, also found in very different situations, as, for example, the epiphytes 
of a typical tropical forest where the atmosphere is warm and damp. Other 
succulent plants inhabit maritime districts, especially the neighbourhood of 
salt-marshes, and others, such as many of the Crassulaceae, though commonly 
found in stony or rocky places, thrive equally well in ordinary soil, and may 
then be freely associated with mesophytes. We may thus distinguish, 
according to their habitat, four main classes of succulent plants, which may 
be briefly designated as (i) Desert Plants , (2) Rock Plants , (3) Epiphytes , 
(4) Halophytes. 
We are naturally led to ask how far the succulent habit is to be 
regarded as an adaptation to environment in all these cases ; and in the 
Annals of Botany, Vol. XXVI. No, CII. April, 1913.] 
