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between the highest point of the buttress on the tree and the 
farthest point of the buttress from the tree on the groun 
The following are examples of observations made in the West 
African Rain Forests to illustrate this constancy of shape. 
Group I.—Trees possessing stilt-roots or buttresses arising 
in the upper angle of sub-aerial roots, developing imperfectly or 
rarely perfectly formed plank buttresses :— 
Rhizophora. 
roannging 
Ficus 
M esti 1 Smithii. 
Tarrietia utilis (if buttressed, the height of the buttress phe 
the length of the base, and the hypotenuse is straight) (Fig. I.). 
Group II.—Trees possessing perfectly formed plank buttresses, 
which arise in the angle of the stem and lateral surface roots :— 
a. Hriodendron. The height of the buttress equals or is 
Bombax. double the base and the hypotenuse 
is straight or concave (Fig. II.). 
b. Piptadenia, The height equals (Fig. II.c.) or is half the 
Parkia. length of the base and the hypotenuse 
is straight (Fig. IIT.). 
ce. Entandrophragma. (The height is less than half the length of 
hira. the Bis and the hypotenuse is concave 
(Fig. I 
d. Terminalia. f 
Anopyxis. The height equals the base, me the 
Khaya. hypotenuse is straight (Fig. ; 
Triplochiton. 
e. Cynometra sp. The height equals the base, and the 
(Ananta, Twi). hypotenuse is convex (Fig. V.). 
Group III.—Trees with stems deeply furrowed or fluted 
towards the base but not possessing any real buttresses, 
(Fig. VI.) :— 
Alstonia congensis. 
Chlorophora excelsa 
Cylicodiscus gabunensis. 
Group [V.—Trees with cylindrical trunks right to the base :— 
Mimusops. 
Further investigation of this subject may provide information 
of much assistance in the identification of trees in the forest, 
where only the base can be seen and the crowns are hidden 
in the tangled canopy above. 
