34 LABORATORY STUDIES OF THE ROOT 



summary could come only after a good deal of looking into particular cases. 

 Observations should be numbered in the notebooks; and specimen parts of 

 the plants whose buds are described should be kept properly numbered, for 

 determining with certaintj'^ what the plants are that have been studied. There 

 are several j^opular works from which the names of plants in flower, or of trees 

 even not in flower, may be made out to some extent. If one learns the use 

 of the Manual, names may be determined without other help. Assistance 

 may often be had from a trained botanist through correspondence, if none is 

 available near at hand. 



I. Summer. Growing buds. Protection of the tender tips : against (a) in- 

 sects, (6) S7iails (water plants and low under-herbs) , (c) any other animals ? 

 {d) excessive light, heat, and drying; by means of (a) stipules, {h) petioles 

 of older leaves, (c) trichomes, (d) convergence and overshadlng by all the 

 parts generally, (e) other arrangements. 



II. Summer, fall, and winter. Resting (or "winter") buds. A. When 

 are they formed, in different plants ? B. Sources of danger. Determine some 

 of these by actual observations on (a) birds — e.g. note the food of flocks of 

 northern birds that visit your locality in winter — and (6) other animals. 

 As to temperature, it may be asked. Do huds freeze? Does freezing kill? 

 Does prolonged freezing kill? Does thaioing kill? C. Methods of offsetting 

 the dangers by (a) special scales (what is the nature, or morphology, of the 

 scales?), (6) coatings of the parts (wool, glandular secretions), (c) seclusion 

 (1) under bark, (2) in hollows, (d) other means. 



III. Experimental. Earliest date at which buds of different species can be 

 made to open, within doors. Effects of removing some or all of the scales in 

 certain species. Do buds grow at all, in diameter or length, between Decem- 

 ber 1 and March 1, or otherwise change? 



V. LABORATORY STUDIES OP THE ROOT 

 Exercise XIV. The General Morphology of the Root 



The root suggested is that of Shepherd's Purse. (Do not remove 

 the leaves from the plants.) 



Note the general habit of the root system, consisting of one main 

 root (taproot), and numerous lateral roots and rootlets. 



What is the direction of growth of the taproot? Of the lateral 

 roots ? Examine the taproot with the lens for contraction wrinkles. 

 Of what service is contraction of the roots, in the case of such a plant? 



Place some of the fine, fibrous rootlets on the stage of the dissecting 

 microscope in water, and carefully pick apart with needles, so as to see 

 their length, branching, and relative slenderness. Can root hairs be 

 made out? Does the branching show regularity? Is the root jointed 

 where branches spring out? At w^hat angle do the branches spring? 



Chip away one side of the main root to show the w^ood at the center. 

 (In doing this, save half or more of the upper part uncut, for later 

 use.) This is the central cylinder. All outside of this is the cortex 

 (bark). By scraping and stripping, a distinct external layer, like a 

 skin, may be detached from the taproot. This resembles the external 



