C14 REV. GEORGE HENSLOW ON THE ORIGIN OF 
then pursued to the 12th. The spiral method is once more resumed as far as the 16th 
braet, when it again changed and finally proceeded on the oscillating system to the apex- 
Such changes as described in the last example seem to be due to the fact that the 
flowers are so crowded that it would appear to be a mere accident, so to say, as to which 
of two opposite bracts became slightly elevated above its companion. The arrangement, 
however, is immediately affected by it. Whenever the internodes between the bracts are 
well pronounced in Lathrea, then the oscillating plan is for the most part adhered to 
with precision. 
Fig. 3 represents another example of Lathrea in which frequent changes were exhibited. 
It will be easily understood from what has been explained with reference to fig. 2. 
The next plant to be referred to is Silene pendula. 
De Candolle *, in describing the scorpioid cyme, refers the reader to species of Silene 
with *'spicate" or, rather, “racemose” inflorescences, as being reduced forms of the 
* dichotomous eyme " so common in other species of Silene as well as of the Caryophyllee 
generally. “In this case," he says, ** the flowers are generally arranged on one side "— 
i. e. more or less inclined to be secund—“ either by a tendency of the branches to abort 
on the same side, or by a torsion of the axis. The branches or stems in which this dis- 
position takes place are in general before their development rolled into a volute on the 
exterior side;" and he mentions Drosera, *spicate" species of Silene, Echium, and 
other Boraginaceous plants. De Candolle designates such unilateral inflorescences by 
the name cimes scorpioides T. 
Before I was aware that De Candolle had referred to Silene at all, my attention 
happened to be drawn to the subsecund arrangement of the flowers of Silene pendula; 
and it occurred to me that it might throw light on the origin of the scorpioid cyme, 
which I had always thought to be erroneously explained in text-books. 
The inflorescence of Silene pendula (fig. 9) consists apparently of opposite and decussate 
bracts; and if it be held before the observer so that one flower faces him, the next flower 
is in the axil of the bract (say, to the right hand); the next is over the first and also faces 
him, the fourth being over the second (again on the right hand), and so on. Hence the 
flowers are in two vertical rows at an angular distance of 90° apart. On the other hand 
there are two rows of bracts, also 90° apart, which have no flowers in their axils. 
Moreover, the bracts beneath the flowers are all much more reduced in size than those 
opposite to them, showing a strong tendency to be arrested. Lastly, there is a great 
propensity for all the flowers to turn to one side. 
It may be added that in Silene there is no tendency to produce any disarrangement in 
the opposite and decussate bracts +. 
* Organographie végétale, i. p. 413 seg. 
+ He here uses the word “ volute;" but it does not appear to have been intentional to express the conical form 
of spiral indicated by the term, but rather the flat; “ helix.” 
+ Silene pendula has all the appearance of being a monopodial raceme; and had we not other members of the o 
genus (or of the family Caryophylleæ), such as S. calabrica, which produce true dichotomous cymes below and ` 
similar “ racemose " branches above, it would be impossible to interpret the inflorescence of the species aright. - As 2 » 
it is, ho ue, I think we miser tae each flower as a terminal blossom, one ee ee ae veloped, 
