294 



The Journal of Heredity 



Number and Length of Inter nodes. — 

 As a rule most types possess 6 or 7 

 internodes, seldom 5. Concerning the 

 length of the different internodes the top 

 internode is always the longest. The 

 length decreases downward, so that the 

 base internode normally is the shortest. 



Comparing different forms, the lengths 

 of the internodes vary, absolutely speak- 

 ing, to a considerable extent, a fact that 

 causes the various length of stem in 

 various forms. Not only absolutely 

 but also relatively considered, the length 

 of the internodes is varying to the extent 

 that the relation between the different 

 internodes in this respect is rather 

 different in different forms. The top 

 internode may, for instance, in some 

 forms be longer than half the stem's 

 length, whereas in others it hardly 

 equals one-fourth of the whole length. 

 The base internodes are in certain cases 

 very short, in others rather long (see 

 Fig. 3). In this respect the modifica- 

 tions are remarkable, but regarding the 

 length of the internodes there exists, 

 no doubt, a wide range of hereditary 

 gradations. 



Thickness of Stem. — As a matter of 

 course there generally exists between 

 tall and short stem-forms rather great 

 differences in thickness, a fact, however, 

 that also may be noticed between forms 

 of about the same height, so that length 

 and thickness of stem are not always 

 correlated. The thickness of stem is 

 naturally an hereditary character. 



Direction of Stem. — In most timothy 

 forms the stems are stiffly erect, in 

 some, however — for instance, in several 

 dwarfed varieties — they are more or 

 less spreading, but mostly they have a 

 comparatively irregular direction, vary- 

 ing from erect to spreading or at least 

 a tendency towards spreading (see Figs. 

 1 and 5). In other varieties the stems 

 are decidedly spreading, sometimes mak- 

 ing an angle of only 30 degrees with the 

 horizontal level (Fig. lb). Direction of 

 stem is an hereditary character and has 

 a practical bearing. 



Size and Color of Leaves.— In width 

 and length as well as in their mutual 

 relations the leaves vary considerably. 



The middle leaves, which are the largest, 

 may in different forms vary in width 

 from 4.6 to 10.6 mm. and in length 

 from 55 to 276 mm. The relation 

 between width and length of leaves is 

 subject to a wide range of variation; 

 the length of the middle leaves varies 

 in different forms from 14 to 40 times the 

 width. Thus there exist many combina- 

 tions of gradations that certainly are 

 hereditary, though it is very difficult to 

 arrive at a definite conclusion in this 

 respect. The leaves may also be flat 

 or more or less boat-shaped. 



As to direction of leaves, in most 

 forms the leaves are drooping, in some 

 nearly erect. The color of the leaves 

 varies from pale green to dark or bluish- 

 green. The stems are normally yellow- 

 greenish; at times the upper internodes 

 may be rather intensely anthocyan or 

 bluish colored. 



Variation of Head. — The head is sub- 

 ject to marked variations in length, 

 thickness, shape, stiffness, compact- 

 ness, etc. (see Fig. 3). Length and 

 thickness of the head change markedly. 

 No correlation exists between these 

 characters, as in two variations of like 

 length of head the thickness may dif- 

 ferentiate considerably, and vice versa. 

 It may be stated that the length of 

 head varies from 2 to 15 cm. and the 

 thickness from about 3 or 4 mm. to 

 8 or 10 mm. Different gradations of 

 size of head are obviously hereditary. 

 The shape of head is normally cylin- 

 drical, occasionally with tapering apex 

 or base, rarely fusiform, all of these 

 characters being surely hereditary. As 

 a rule the head is stiff, occasionally 

 slender and nodding. 



In the typical timothy head the 

 rachillae are reduced to such an extent 

 as to give the 1 -flowered spikelets the 

 appearance of growing out directly from 

 the spike axis; in exceptional cases the 

 rachillae are elongated, making the 

 spike more panicle-shaped. Also these 

 characters are hereditary (see Fig. 3). 



Variation in Flower Parts. — The 

 empty glumes vary in size from 2.5 or 

 3 mm. to 5 or 5.5 mm. in length (see 

 frontispiece a, b) as well as in color at 



