ANGIQSPERMS. 
597 
very good examples are afforded by several species of Euphorbia, 
especially E. Lathyris and hel'ioscopia. This form of cyme is not 
essentially distinct from the next, and in the highest orders of 
branching 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 ful'va 
and flava, 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), as in Helianthemum, Drosera, Tradescantia, and Scilla 
biflolia. (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 the Boragineae and Solanacese 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- [^'^^ Nouv. Mem. de la Soc. Imp. des Nat. de Moscow, 
XIII, p. 248]. [Kaufmaim'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 
Bliithen stände, 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 
