SYSTEMATIC BOTANY. O 



three sepals and three petals (i. e., a perianth of six leaves or lobes), three 

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

 pistil with a three or six-celled ovary) the plant is an endogen. 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 name. The parts may be described in this 

 order: Boots, 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 

 proper descriptive terms. Suppose the following to be a description of 

 the plant in hand, the words in parentheses indicating the tecbnical 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 (spatulatc) 

 and no stipules (extipulate. ) The small pinkish 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-lobcd) 

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

 from each other (corolla polypetalous) and very narrow inside the calyx (clawed), tho 

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

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

 aged at the base); the petals 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 and 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. 0, we determine that it belongs 

 under Division 1, because the petals arc 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: "* Pistils more than one and distinct ;" but there is only one pistil incur 

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

 carpel, as shown by single style," etc., but there arc three styles in the pistil of our flowers, 

 so we try "4 {- 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 docs not suit because our pod is not 

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



