SYSTEMATIC BOTANY. O 



three sepals and throe petals (t. c, a perianth of six leaves or lobes), three 

 or six stamens and three or six pistils (generally vmited to form a compound 

 pistil with a three or six-celled ovary) the plant is an endog^en. When 

 the leaves are netted-veined, and the parts of the flower are not all in 

 threes, the plant is an exogen. 



49. It is a good plan to write out a description of a plant before 

 attempting to ascertain its iiame. The joarts may be described in this 

 order: Itoots, Stems, Leaves, Flowers, Fruit. The roots may be omitted 

 unless they are peculiar. 



50. With the plant before you and the book open at Stems, p. 10, you 

 will be ready to begin the work. The book will generally supply the 

 proi^er descriptive terms. Suppose the following to be a description of 

 the plant in hand, the words in parentheses indicating the technical ad- 

 jectives which would make the description more exact and concise: 



51. An exogenous annual with hairy erect stems about a foot high bearing opposite 

 leaves which are narrow, with the broadest part near the blunt upper end (spatulate) 

 and no stipules (extipulate. ) The small jjinkish flowers grow on short stems (pedicels) 

 close together along one side of the main stem for several inches to the end (in a 

 close raceme); the five Sepals of the calyx unite to form a narrow tube (tubular, 5-lobed) 

 nearly half an inch long, marked by ten ridges (nerves); the five petals are separate 

 from each other (corolla polypetalous) and vc;y narrow inside the calyx (clawed), the 

 part outside (blade) short aud rounded, broadest near the end (obovate) ; two little teeth 

 standing up on each petal just wliere it bends outward from the calyx (blade '2-append- 

 aged at the base) ; the jietals twisted so as to make one edge higher than the other; 

 stamens 10; pistil one, with three short straight styles and a short stem below the ovary 

 (stipe) on which the petals aud stamens grow; the seed pod (capsule) ovoid and rough, 

 containing seeds which grow fast to a central part (placenta). 



52. Turning to the Analytical Key for Exogens, p. 9, we determine that it belongs 

 under Division 1, because the petals are separate. Since our plant cannot belong under 

 A, the stamens being only 10, we turn to "B. Stamens 10 or less," etc.; under this 

 head we read: "1 Ovary or ovaries superior," etc., which is the case with our plant; 

 then follows: "*Pi-'iiils more than one and distinct ;" hnt there is only one pistil in our 

 flower, so we pass onto "**Pistil only one," below which is " +- Simple, i. e., of one 

 carpel, as shown hij sintjle style," etc., but there are three styles in the pistil of our flowers, 

 so we try "-{--(- Pistil compound," etc., which suits our case; then we read the next 

 line, but upon looking up the word "placenta," conclude that our plant cannot be found 

 under that head; the next line of the same length does not suit because our pod is not 

 "2-celled;" but the third reads: "Ovary and capsule 1-celled, seeds on a central 



