e. Thorns and spines. 
f. Water reservoirs. 
eg. Increase of root system. 
C. Hydrophytes, or hydrophytic structures. 
I. Water plants. 
1. Provision for attachment. 
2. Provision for floating. 
3. Provision for aeration. 
4. Provision for distribution of food. 
5. Provision for fruiting. 
6. Little development of mechanical tissue. 
2. Swimming plants. 
3. Land hydrophytes. 
D. Mesophytes (Tropophytes). 
I. Subject to medium conditions of environment. 
Extremes of heat in general detrimental to 
vegetation when accompanied by dryness. 
Compare resistance of seeds, spores ,etc. 
2. Tropical region mesophytes. Piant in no dan- 
ger from extremes in damp tropics. It 
reaches its highest development of foliage. 
It is luxuriant and permanent. 
3. Temperate region mesophytes, or tropophytes, 
Growing season. 
cold. 
dry. 
Variation in conditions. 
Provision against injury in fall of leaf. 
Perennial herbaceous tropophytes. 
Annuals and bienniais. 
E. MHalophytes, or halophytic structures. 
I. Xerophytic forms. 
Salt marsh and sait basin plants. Modifi- 
cations similar to those of plants in arid 
regions. 
2) irue halepiaytes: 
Resting season 
F. Plant societies based on structural adaptation, as meso- 
phytes, hydrophytes, xerophytes and halophytes, 
only applicable in extreme cases. 
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