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of long palisade cells over a spongy parenchyma which has 
its lowest (green) layer of cells slightly palisade-like, and 
below this is still another palisade-like layer of cells which 
is colourless and must be designated an aqueous tissue. 
Fig. 66. Ceratocarpus arenarius. A, A young plant with green leaves and 
a few fruits in the axils. May. (natural size). B, An older plant, (reduced 
one-half). C, A branch of B, (X 2). The parenchyma has disappeared 
" and the midribs remain as spines. August. 
Ceratocarpus arenarius L. 
This very common plant occurs both on sandy and 
clayey soil; Fig. 66 shows its appearance. In spring the 
