72 ‘ BOTANY FOR BEGINNERS. [Ch. XT). 
288. Jiliaceous, a corolla with six petals, spreading gradually 
from the base, so as to exhibit a bell-form appearance, as in the 
Tulip and Lily. 
289. Rosaceous, a corolla formed of roundish spreading petals, 
without claws, or with very short ones, as the Rose, and Apple. 
Fig. 50. 290. Papilionaceous, a flower 
> with a banner, two wings, and a 
keel; the name is derived from the 
word papilio, a butterfly, on ac- 
count of a supposed resemblance 
\, to this insect, as in the Pea blos- 
) som, (Fig. 50.) 
‘<j 291. When a corolla is of no 
? determinate form, it is said to be 
anomalous. 
Odour of Flowers. 
292. The odour of flowers has its origin in the volatile oils, 
elaborated by the corolla. 
293. Temperature renders the odours of flowers more or less 
sensible; if the heat is powerful, it dissipates the volatile oils 
more rapidly than they are renewed ; if the heat is very feeble, 
the volatile oils remain concentrated in the little cells where 
they were elaborated; in both cases the flowers appear to have 
but little odour. But if the heat is neither too great nor too little, 
the volatile oils exhale without being dissipated, forming a per- 
fumed atmosphere around the flowers. 
294, You see now the reason, that when you walk in a gar- 
den in the morning, or towards evening, the flowers seem more 
fragrant than in the middle of the day. The air being also more 
damp causes an increase of fragrance at those times, as the 
moisture, by penetrating the delicate tissue of the corollas, ex- 
pels the volatile oils. 
988. What is a liliaceous corolla ? 
289. What is a rosaceous corolla? 
290. What is a papilionaceous corolla ? 
991. When is a corolla said to be anomalous? 
292. What causes the odour of flowers ? 
293. What effect has temperature upon the odour of flowers? 
294. Why do flowers appear peculiarly fragrant in the morning | 
and evenirz ? 
