[19] DIRECTIONS FOR COLLECTING PLANTS KNOWLTON. 



roots, form and direction of branches, if compound; shape, form of artic- 

 latious, if jointed; glabrous, granular, pubescent, or mammilated sur- 

 face; and form of ribs and grooves when present, both in section and 

 profile, especially near the apex of the stem. The last features are best 

 shown in diagrams. Leaves are present in few groups, but when they 

 occur their duration, size, form, and direction are to be noted. All cacti 

 produce more or less wooly or prickly buds, known as areolae, on which 

 the flowers and spines are inserted. It is important to observe whether 

 they are immersed or prominent, and their form and usual distance 

 apart. Young and old areolae should be compared, and particular atten- 

 tion given to the character and color of their wooly or bristly covering. 

 The very characteristic spines occur on the areolae, and differ greatly 

 in number, relative location, size, form, direction, and color, all of 

 which are to be observed. Diagrams aid in showing the form of the 

 areolae and the location and section of the spines. An important char- 

 acter is the stability of the si)ines, for in some species the areolae in- 

 crease in size, and the spines become more numerous from year to j^ear, 

 while in others this change does not occur, and the spines may fall with 

 age. 



" Flowers usually come from areoUie on the sides of the trunk or on 

 undifferentiated branches, but in some genera {Melocacttis f Filocereus. 

 etc.) the sterile and flowering parts are very different. The origin of 

 the flowers (from old, 1-year old, or nascent branches) and their time of 

 expansion (diurnal, nocturnal, or diurnal persisting through the night) 

 should be observed, together with size, shape, color, and fragrance. The 

 form and size of the (hiferior) ovary and the shape, approximate num- 

 ber, and character of the reduced sepals that often cover it, with the 

 nature of the wool, hairs, or spines in their axils, are all important, as 

 are the shape, size, and coating of the tube of the flower. In a longi- 

 tudinal section it is to be observed whether the lower part of the tube is 

 naked or nectariferous within or not, together with the distance from 

 the top of the ovary to the lowest stamens, the presence or absence of a 

 vaulted arch partly closing the tube, and the form and disposition of 

 the stamens. Any color peculiarities of these, and the color, form, and 

 relative length of the style, and especially the stigmas, are to be noted. 

 The shape, color, texture, taste, and odor of the fruit, the presence of 

 scales, and the character of their auxiliary products should be observed, 

 as also whether the flower is withering-persistent on the fruit or decid- 

 uous, and in the latter case the form of the resulting scar (umbilicus). 

 The occurrence of few or many seeds is also important." (George En- 

 gelmann in Botanical Gazette, x\, pp. 135, 136.) 



