THE FOXGLOVE TRIBE. 197 



nature of a little scale which is very often found at 

 the back of the corolla in these two-lipped corollas ; 

 the scale is a stamen in a rudimentary state. 



If you next compare the structure of the Foxglove 

 tribe with that of the Nightshade, you will remark 

 that the resemblance between them is quite as great as 

 between the Foxglove and the Mint tribe ; only in a 

 different way. They both have monopetalous flowers, 

 five divisions of the calyx and corolla, and an ovary 

 with two cells ; but in the Nightshade tribe the 

 stamens uniformly correspond in number with the 

 lobes of the calyx and corolla ; while in the Foxglove 

 tribe they are uniformly fewer ; in a word, the flowers 

 of the former are symmetrical and regular, of the 

 latter, unsymmetrical and irregular, and this is the 

 great distinction between them. 



With this I must abandon the explanation of the 

 Monopetalous Dicotyledonous natural orders, which 

 have more than one carpel in each flower ; my next 

 letter will be confined to those, the carpel of which is 

 absolutely solitary and simple. 



EXPLANATION OF PLATE XVL 



I. The Mint Tribe.— 1. A flower oi Black Horehound (Ballota 

 nigra) ; a, a lobe of the calyx; b, the upper lip of the corolla; c, the 

 lower lip. — 2. A corolla spHt open to shew the position of the sta- 

 mens.— 3. The top of a filament, with its anther.— 4. A pistil; a, 

 a fleshy disk, out of which springs the four-lobcd ovary. — '>. The 

 two lobes of the style. — 6. A ripe fruit before the lobes separate. — 

 7. One of the lobes apart.— 8. A fruit cut through horizontally, 

 shewing the four embryos at a. 



