PENTSTExMON SECUNDIFLORUS. ONE-SIDED PENTSTEMON. I 75 



plants a little deeper than they grew before, every second year 

 or so ; and it is a good plan to raise new plants from seed occa- 

 sionally. 



There are some peculiarities in its botanical characters that 

 will interest the general observer. As already noted it was 

 once supposed to be identical with another known as Pentstcmon 

 aciiminatus. But our present species is strongly two-lipped, 

 which Fig. i particularly well shows, while the other species has 

 a. more nearly regularly divided corolla ; and while that has a 

 tube gradually tapering to the throat, the tube in this species 

 tapers abruptly to the throat, as we see in Fig. 2. And then the 

 other species has the flowers arranged regularly around the 

 stem, while this, as we see in our drawing, has all the mouths of 

 the flowers looking towards us, or one-sided — in botanical lan- 

 guage they are secund. Why flowers should have this one- 

 sided habit of flowering has not been examined till recently ; 

 but there is now good reason to believe that it is because each 

 alternate flower twists in the opposite direction to the other. 

 That is^to say that there are two distinct lines of spiral growth 

 in some plants, the one turning to the right, the other to the left, 

 and which must of necessity result in a one-sided raceme. In 

 the transition from leaves to flowers we may also see an inter- 

 esting form of gradadon, by no means uncommon, but yet 

 worth noting in our specimen. The root-leaves and those on 

 the barren shoots, as Fig. 3, are broader at the end than at the 

 base ; but as the branch proceeds to form the inflorescence, the 

 apex becomes narrower than the base. It is of course well 

 known that flowers are made up of modified primordial leaves. 

 In our days we are getting an insight into the process, as well 

 as having a knowledge of the fact ; and one of these new pieces 

 of knowledge is, that when a petal is formed from an original 

 and, we will say, microscopic leaf, it is generally by a suppres- 

 sion of the elongating part or mid-rib, and a widening of the 

 base. Thus, in an auriculate or eared leaf, it is the auricle, or, in 

 some cases, the stipule, out of which the future petal is formed. 



