LESSON 31.] HOW TO STUDY PLANTS. 191 



cotyledons (as in Fig. 26), readily inspected if we have seeds, 

 show it belongs to Class I. Its pistil refers it of course to Subclass I. 

 The corolla being a short funnel-shaped tube, theoretically regarded 

 as formed of five petals united up to the very summit or border, ren- 

 ders the flower a good illustration of the MONOPETALOUS DIVISION, 

 the analysis of which begins on p. 20, in the work we are using. 



554. The calyx free from the ovary excludes it from the section 

 A, and refers it to section B. This is subdivided, in the first place, 

 by the number of the stamens, and their position as respects the 

 lobes of the corolla. Now, as the petals of the corolla in this flower 

 are united up to the very border, the student may at first be puzzled 

 to tell how many lobes it should have, or, in other words, how many 

 petals enter into its composition. But the five leaves of the calyx 

 would lead one to expect a corolla of five parts also. And, although 

 there are here really no lobes or notches to be seen, yet the five 

 plaits of the corolla answer to the notches, and show it to consist of 

 five petals perfectly united. Since the stamens are of the same 

 number as the plaits of the corolla, and are placed before them (as 

 may be best seen by splitting down the corolla on one side and 

 spreading it out flat), it follows that they alternate with the lobes or 

 petals ; therefore our plant falls under the third subdivision : " Sta- 

 mens as many as the lobes or parts of the corolla and alternate with 

 them." This subdivides by the pistils. ^Our plant, having a pistil 

 with two stigmas and two cells to the ovary, must be referred to the 

 fifth and last category : " Pistil one, with a single compound ovary,'* 

 &c. We are then directed to the stamens, which here are " plainly 

 borne on the corolla " ; next to the leaves, which are on the stem 

 (not all at the root), also alternate, without stipules; the stamens 

 5, and the ovary 2-celled, all of which accords with the seventh 

 of the succeeding propositions, and with no other. The middle one 

 alone under this agrees as to the ovary and seeds, and all is confirmed 

 by the twining stem. It is the CONVOLVULUS FAMILY, p. 262. 



555. The proper Convolvulus Family has green foliage, as has 

 our plant. Its style is single and entire, as in 1. Its calyx has a 

 pair of large leafy bracts, as in the subdivision with two stars. So 

 we reach the genus CALYSTEGIA, or BptACTED BINDWEED. 



556. Under this genus two species are described : the twining stem, 

 and the other particulars of our plant, direct us to the first C. SEPIUM, 

 which in England is named HEDGE BINDWEED, and here is one 

 of the various Convolvulaceous plants known as MORNING-GLORY. 



