196 LETTER XVI. 



Thus Figwort (Scrophularia) has a globular corolla, 

 \\'ith a large upper, and a very small lower lip ; 

 Speedwell (Veronica), ^dth its spikes of blue, has only 

 two stamens; S?iapdrago7i( Ant\rrhmum)hsiS the throat 

 of the lower lip so prominent as to press against the 

 upper ; Mo7ikey jioicers (Mimulus) have the angles of 

 the calyx winged ; and the woolly Mulleins (Verbas- 

 cum), a corolla with scarcely any tube. No genus is 

 more remarkable than Pentstemon, of which so many 

 fine American species adorn our gardens ; in that 

 plant there are actually five stamens, four of which 

 are of two different lengths, as is usual, while the fifth 

 is long and slender, very hairy at the point, and 

 projects into the very mouth of the corolla ; it is, 

 however, notwithstanding its size, imperfect : for it 

 bears no anther. This plant is interesting, as shew- 

 ing that in such irregular flowers as those of the Mint 

 and Foxglove tribes, there is a tendency to become 

 regular, which is sometimes very strongly manifested. 

 To render a Foxglove regular, it should not only have 

 the divisions of its calyx and corolla of the same 

 size, and of the same number ; but the stamens 

 should agree in number with those ; that is to say, 

 as there are five sepals and five lobes to the co- 

 rolla, there should also be five stamens, instead 

 of four, to constitute perfect regularity. It is con- 

 sidered that in those plants in which there are only 

 four stamens, the fifth is abortive or undeveloped, 

 and that when two stamens only appear, the three 

 others are abortive. This will explain to you why a 

 fifth stamen appears in Pentstemon ; and also the 



