ANGIOSPERMS, 597 



very good examples are afforded' by several species of Eufborbia, 

 especially E. Lathyris and helioscopia. This form of cyme is not 

 essentially distinct from the next, and in the highest orders of 

 brapching commonly passes into it ; in Periploca grceca, for example, 

 even in the first ramification. 



12. The Dichasium : Each primary axis terminating in a flower produces 



a pair of opposite or nearly opposite lateral axes, which in their turn 

 produce pairs of the second order, and so on. The whole system 

 appears as if composed of bifurcations, especially after the older 

 flowers have fallen off; as in Euphorbia, many Sileneae, some Labiatae, 

 &c. The dichasium easily passes, in the first or a succeeding order 

 of lateral axes, into a sympodial mode of development. 



b. Cymose Inflorescences nvith a Pseud-axis {Sympodial Inflorescences'). Each axis 

 which terminates in a' flower bears only one lateral axis of the next order. 

 The basal portions of the consecutive orders of axes may lie more or less in 

 a straight line, and may become thicker than the flower-stalk (above the 

 branching). A pseud-axis or sympodium may thus become either straight or 

 curved first in one direction and then in another, the flowers appearing to be 

 produced on it as lateral shoots (see Fig. 136, A, B, D, p. 180). If the sym- 

 podium is clearly developed, it resembles a spike or raceme, from which 

 however it is easily distinguished when bracts are present by their being 

 apparently opposite to the flowers (as in Helianthemum) ; but displacement 

 not unfrequently causes it to assume a different form (as in Sedum). 



13. The Unilateral Helicoid Cyme (Bostryx) is a sympodial cyme in which 



the median plane of each of the successive axes which constitute the 

 system is always situated on the same side, whether right or left, 

 with respect to the preceding one (see Fig. 136, D) ; as for instance, 

 in the primary branches of the inflorescence of Hemerocallis fulva 

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

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



14. The Unilateral Scorpioid Cyme (Cicinnus) is one in which the successive 



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

 (Fig. 136 A)i as in Helianthemum, Drosera, Tradescantia, and Scilla 

 'bifolia. (Hofmeister.) The inflorescence of Eche'veria 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 the Boragineae and Solanaceae differ both in their mode of 

 development and in their external appearance from the plan described in B b, Kaufmann 

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



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

 XIII, p. 248]. [Kaufmatm's observations have been confirmed by Warming (Ramification des 

 Phanerogames, 1872), by Pedersen (Bot. Tidskrift, 1873), and by Kraus (Bot. Zeitg. 1871) in so 

 far as bracteate scorpioid cymes are concerned. (See also Wydler, Zur Morph. d. dichotomen 

 BlUthenstande, Jahrb. f. wiss. Bot. XI, 1878). Warming considers that dichotomy also occurs in 

 naked scorpioid cymes, but Kraus states that these are monopodial, and Warming admits that lateral 



