STRUCTURE AND PECULIARITIES. 17 
are easily distinguishable; but in such monocotyledons as 
the Hyacinth or Tulip, the petals and sepals are almost or 
quite undistinguishable, and the whole flower goes by the 
mame of a perianth; the three outer segments being, 
strictly speaking, sepals, and the three inner, petals. In 
Orchidacez there is usually a marked irregularity in the 
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os eee, ig 
\ sun 
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Fig, 1. Flower of Vanda Cathcartii 
(nat. size). 
shape of the flower, the nature of which will be made 
clear by the accompanying Figure. We have, outside, a 
row of three sepals (s, Fig. 1); then come three petals (J), 
two of which usually more or less resemble the sepals in 
shape and colouring, while the third petal (as we may 
consider it for practical purposes), which usually differs 
considerably in size, colour, and form, and is the lowest 
fs 
