372 



Tricot \lous Races. 



perennial plants, the transition from one mode of ar- 

 rangement to the other has been frequently observed 

 on the same axis, as Delfino has shown, I need not 

 enter further into it now. Sometimes it happens also 

 that the main stem of a tricotylous plant bears its leaves 

 in quaternary w-horls (Scabiosa atvo purpurea). 



Fasciations are a frequent consequence of tricotyly, 



though they sometimes do not 

 ai)pear until late in the life 

 of the plant. Merciirialis an- 

 nua and Ajuaranfus speciosus 

 furnished a series of instances 

 nearly every year during sev- 

 eral years of culture. In the 

 former species they usually 

 appear low on the stem ; in 

 the latter not below the in- 

 florescence (See Fig. 83, p. 

 399). My tricotylous race of 

 Mercurialis annua furnished 

 almost all forms of fasciation. 

 Fig. 77 represents a tricotylous 

 plant whose stem was split 

 from the first node after the 

 cotyledons, and was therefore 



Fig. yy. Mercurialis annua. 

 A, tricotj'lous seedling with 

 split stem; B, a seedling the 

 first whorl of leaves of 

 which was ternary ; C, hemi- 

 tricotylous plant (1900). 



only fasciated in the epicotvl- 

 ous internode. Between this condition and a flat stem 

 one centimeter broad, and much contorted, all inter- 

 mediate stages are presented by this species. In the 

 spring of 1887 I collected a large group of hemi-tricotyl- 

 ous, tricotvlous and tetracotvlous seedlings fSee Fisf. 

 70) of Acer Pseudo-PIafanus not far from Hilversum 

 and grew them for several years. Most of them I threw 



