VARIATION IN TIMOTHY HEADS 



This series of heads represents the range of variation which has been obtained during the 

 course of the breeding work at Svalof. "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 ob- 

 viously hereditary." (Fig. 3.) 



bloom and maturity. The floral glumes 

 are also subject to variability as to form, 

 size and color. Normally the first 

 floral gliune is awnless, occasionally 

 having a small awn (see Fig. 2, c-h). 

 The anthers vary in color from white to 

 intense violet, sometimes rust-brownish. 

 The grains present variations in form 

 (roundish or pointed), color (light to 

 dark brown) and size (see Fig. 2, i-m). 



Physiological Characters. — Regarding 

 hardiness no difference between various 

 forms has been noticed at Svalof, but 

 in the northern part of Sweden, at the 

 branch station of the Swedish Seed 

 Association at Lulea, Lat. 65° 35' N., 

 marked variations in this respect have 

 been noted. 



Different timothy forms present a 

 noticeable variation in earliness of 

 shooting culms in spring time as well 

 as in earliness of bloom (see Fig. 5). 

 The beginning of the bloom time may 

 differ with twenty-five days between the 

 earliest and the latest forms. These 

 characters are anyway not correlated, 



296 



but hereditary. Stiffness of stem ap- 

 pears to vary as in the cereals and is also 

 hereditary. Withering down of leaves 

 is an hereditary character that may be 

 very pronounced. In some forms all 

 the leaves may be withered at the begin- 

 ning of the bloom; in others they may 

 be almost fresh even at the ripening of 

 the seeds. 



Aftergrowth. — The quantity of the 

 aftergrowth is to a large extent due to 

 more or less favorable conditions of 

 weather, but also to different forms. 

 Some forms yield exclusively leaves, 

 others leaves and stems, and others again 

 nothing but single stems (see frontis- 

 piece). As to stooling power there is a 

 wide range of variation in different 

 forms. 



Disease Resistance. — ^The resistance 

 against the timothy rust (Puccinia 

 phleipratensis) , the fungous disease that 

 most severely attacks timothy, varies 

 considerably in different forms. Some 

 forms are so intensely affected that rust 

 appears even in the empty glumes, 



