Tricotyly and the Arrangement of Leaves. c>7^ 



away as soon as they rexerted to the decussate arrange- 

 ment of their leaves, but seven of these trees are still 

 alive, two with ternary stems (p. 370), two with a de- 

 cussate arrangement of the leaves, and one with a much 

 flattened main stem. This last one began with three 

 cotyledons; it then became decussate, and in its second 

 year (1889) became ternary again. In the autumn of 

 the following year it began to flatten out, formed three 

 five-leaved whorls and began to split when laying down 

 the winter bud. I then broke off all the terminal buds 

 except one, which in the spring of 1891, during sub- 

 sequent growth, split into three flat twigs of which 

 again two were removed. In the following summer the 

 fasciation recurred, and also, after splitting in the win- 

 ter, in the next year (1892), and again in 1893. Every 

 time the forked branches were reduced to one. The 

 divisions became much rarer, later on, and the older sec- 

 tions of the stem which were at first flat gradually be- 

 came cylindrical, as usually happens in fasciation when 

 it afl^ects trees. ^ 



On tricotylous specimens I also observed flattened 

 stems in Antirrhhinm ma jus, Artemisia Ahsynthium, Sca- 

 hiosa atropiirpurea, Dianthus pliimariiis, CoUinsia hetero- 

 pliylla, C. grandiflora, C. violacea and Tetragonia ex- 

 pansa (Fig. 78) ; and amongst tetracotyls in ScropJui- 

 laria nodosa and Colli nisia z'iolacea and other species.- 



In many cultures I have observed that fasciations are 

 more common amongst tricotylous plants than amongst 

 dicotylous ones, but I shall only deal in detail with an 

 experiment on Aspenda aziirea. In the spring of 1892 

 I selected the hemi-tricotylous, tricotylous and tetra- 



'^ Kruidk. Jaarh. Gent, 1894, Plate XI, {Abies excelsa). 

 ^Ber. d. d. hot. Gcs., Vol. XII, p. 36. 



