68 
CONTRIBUTIONS TO BOTANY. 
as shown by Plumier in Bignonia crucigera (PI. Am. Burm. tab. 78. 
fig. A), and by Gaudichaud in Bignonia capreolata, B. unguis, 
B. lactiflora, &c. (Rech. Org.Veg. tab. 14. fig. 4; tab. 18. figs. 4, 
5, 6, 7, 8, 9 & 10). The latter botanist remarks that this pecu- 
liarity is more strongly developed in the plants of equatorial 
regions : he adds that only four cruciform rays are at first seen ; 
subsequently these are increased to eight, then to sixteen, thirty- 
two, &c., and always in this geometrical pro- 
gression. I possess the stem of a Bignoni- 
aceous climber from the region of the Organ 
Mountains ; it is deprived of its bark, and is 
about an inch in diameter : here four principal 
rays are prominently developed, with four other 
intermediate rays less strongly marked (fig. 20) ; 
and corresponding with these rays, the stem has eight deep, 
longitudinal, broadly gaping fissures, that run through its 
entire length and extend half-way towards the centre. In these 
fissures, at intervals of every 4 or 5 inches apart, are seen the 
sprouts branching from the centre, out of which the decussating 
opposite leaves have originated ; and it is to be remarked that 
these leaf-sprouts are always found in the four alternate grooves 
which correspond with the secondary set of medullary rays above 
mentioned. Each of these axillary sprouts is formed of a con- 
geries of four sets of concentric plates united together in one 
common bundle — a structure probably connected with the deve- 
lopment of conjugate leaves. The wood is extremely light and 
porous, and I believe it to be the stem of Bignonia Rego, Veil., 
the Arrahidea Rego, DC. (misspelt Sego in the ‘Prodromus^) *. 
I have not seen any specimen of this plant, and have some doubt 
whether it be a true species of Arrabidea ; at all events, it must 
not be taken as the type of the genus, though placed first on its 
list in the ‘ Prodromns ’ by DeCandolle, who appears to have 
known it only from Velloz’s drawing. 
In the ‘ Prodromus ’ of DeCandolle too much Importance has 
been assigned to the form of the calyx as a generic feature of 
distinction : on the one hand, this distinction has been little 
attended to in the selection of the species under the different 
genera, as in Cuspidaria, Arrahidea, Tahebuia, &c.; while, on the 
other hand, many species, genericaUy distinct, are brought to- 
* This error has originated in copying the name from the lithographed 
plate of the ‘ Flora Fluminensis,’ executed in Paris, in which work nume- 
rous similar misnomers occur. Had DeCandolle referred to the text of 
that work, he would have discovered the mistake, and have called the 
plant Arrabidea Rego : the latter is a Portuguese word signifying a rent or 
fissure, in allusion to the fissures I have described, and which are represented 
in the plate referred to, vol. vi. tab. 39. 
Fig. 20. 
