5 2 2 PHA NER G GA MS. 



primary branches of the inflorescence of Hemerocallis ful-va and 

 Jia'va, and in the partial inflorescences of Hypericum perforatum 

 which are themselves arranged in a panicle. (Hofmeister.) 



14. The Unilateral Cicinal {Scorpioid) Cyme is one in which the successive 

 axes arise alternately to the right and left of the preceding one 

 (Fig. 128 A) as in Helianthemum, Drosera, Tradescantia, and Scilla 

 hifolia. (Hofmeister.) The inflorescence of Echeveria belongs also 

 to this kind of originally monopodial sympodium ; the mature cyme 

 has a pseud-axis on which the flowers are placed opposite the 

 leaves. While the summit of each successive axis is converted into 

 a flower, a lateral axis arises in the axil of the subtending leaf. This 

 lateral axis developes further, forms a new leaf in a plane nearly at 

 right angles to the last, and becomes transformed into a flower, 

 while a lateral axis appears in the axil of its leaf which continues 

 the development ; the leaf which arises on this axis is in the same 

 plane as the last but one. (Kraus.) 



The inflorescences of Borragineae and Solanaceae diff'er both in their mode of de- 

 velopment and in their external appearance from the plan described in B b. Kaufmann 

 has already stated ^ that the inflorescence of some Borragineae is the result of repeated 

 dichotomy of the apex of an axillary bud ; and Kraus has also shown '^ that the leafless 

 inflorescence of Heliotropium and Myosotis is a monopodium, at all events when luxu- 

 riant. A thick and flattened vegetative cone developes two alternate rows of flowers 

 on its upper side; on this side the longitudinal growth of the primary axis is at first 

 stronger ; and the younger part of the inflorescence is consequently rolled with its apex 

 downwards in a clrcinate manner. An inflorescence which is formed in this manner, 

 as will be seen from what has already been said, cannot properly be described as a 

 scorpioid cyme, but corresponds rather to a raceme or spike which bears flowers only 

 on one side of its rachis. The leafy scorpioid cymes of Anchusa, Cerinthe, Borrago, 

 and Hyoscyamus are, on the contrary, the result of dichotomous branching; a leaf 

 which stands on the primary axis ending in a flower bears in its axil a vegetative cone 

 which is at first hemispherical ; this becomes broader and dichotomises in a direction 

 parallel to thetsurface of the leaf; one of the bifurcations becomes a flower, the other 

 forms a new leaf at right angles to the last, and above it a dichotomy as before. The 

 planes of dichotomy therefore cross one another at right angles; and this is the reason 

 why the leaves always stand between the sympodial axis and the flower. Lateral dis- 

 placements of the leaves begin at the second division and continue afterwards. 



According to Kraus it is doubtful whether the sympodial inflorescences of Ompha- 

 lodes and Solanum nigrwn are the result of dichotomous or of lateral branching. On 

 the side of the primary axis which becomes a flower a leafless lateral axis arises which 

 continues to branch, and the right and left lateral axes of which are alternately trans- 

 formed into flowers. Kraus entertains a similar doubt respecting weak inflorescences 

 of Myosotis and Heliotropium (yide supra). 



It will be seen from what has now been said, that within an inflorescence which 

 consists of several orders of axes there may be produced not only different forms 

 of one section, but forms belonging to both sections (^A and B), mixed inflorescences 

 being thus formed. Thus, for example, a panicle may form dichasia in its last ramifi- 



^ Kaufmann, Bot. Zeitg. 1869, P- 886 [and Nouv. Mem. de la Soc. Imp. des Nat. de Moscow, 

 XlII, p. 248. See also Warming, Recherches sur la ramification des Phanerogames, Vid. Selsk, Skr. 

 5 R. Afd. 10 (with French abstract). He confirms the view that the scorpioid cymes of Borragineae 

 and Hyoscyamus originate through dichotomy. — Ed.] 



^ Kraus, Sitzungsberichte der med.-phys. Soc. in Erlangen, Dec. 5, 1870. I have also derived 

 a part of the above fiom correspondence with Kraus. 



