ON THE FERTILIZATION OF LYTHRUM SALICARIA. 169 
integra, glabra, supra lucida; nervi laterales 12-15 utrinque costaque 
utraque pagina prominuli; petiolus usque pollicem fere longus, teres, 
glaber. Amenta axillaria, geminata, rarius abortu solitaria, breviter 
(i poll.) pedunculata, subtus nuda, supra floribus masculis densissime 
obducta, foemineis paucis multo majoribus intermixtis.  Bracteola 
trigono-peltate, minutz, pilosule, ciliolatze, virides. Flores sessiles, 
compacti, viridiusculi, dein Since nies: Sepala florum masc. basi in 
tubum brevem connata, extus pilosula, ea flor. foem. libera, exteriora 
pubera, dein hirtella, interiora lzvia, teneriora. Achzenium pisi majoris 
magnitudine, stylo persistente auctum, perigonio hirtello inclusum, 
maturescens contactu etiam levi elastice (ad 6 metr.) exsiliens. 
In sylvis Sumatra; in prov. Palembang; in prov. Padang prope Lumut et 
ad littora prope Siboga, Teijsmann. Ins. Singapora, T. Anderson, M.D. 
Nom. vernac. Kapinie. 
Synon. Artocarpus elongatus, Mig. Fl. Ind. Bat. Suppl. p. 172 et 419. 
Tas. XIII. fig. 1. Ramus floriferus magnit. nat.; fig. 2. Flos d et 9 
auct. ut fig. sequent.; fig. 3. Sepalum.exter. fl. ? a dorso; fig. 4. 
Sepal. inter. fl. 9; fig. 5. Ovarium; fig. 6. idem, verticaliter transsect. ; 
fig. 7. Semen, tegmento remoto. 
On the Sexual Relations of the Three Forms of Zythrum salicaria. 
By CHARLES Darwk, F.R.S., F.L.S., &c. 
[Read June 16, 1864. ] 
Some of the species of Lythrum offer in their manner of ferti- 
lization a more remarkable case than can, perhaps, be found in 
any other plant or animal. In Zythrum salicaria three plainly 
different forms occur: each of these is an hermaphrodite, each 
is distinct in its female organs from the other two forms, and 
each is furnished with two sets of stamens or males differing 
from each other in appearance and function. Altogether there 
are three females and three sets of males, all as distinct from 
each other as if they belonged to different species ; and if smaller 
functional differences are considered, there are five distinct sets 
of males. Two of the three hermaphrodites must coexist, and the 
pollen be carried by insects reciprocally from one to the other, 
in order that either of the two should be fully fertile; but unless 
all three forms coexist, there will be waste of two sets of stamens, 
and the organization of the species, as a whole, will be imperfect. 
On the other hand, when all three hermaphrodites coexist, and 
the pollen is carried from one to the other, the scheme is perfect ; 
there is no waste of pollen and no false co-adaptation. In short, 
nature has ordained a most complex marriage-arrangement, 
namely a triple union between three hermaprodites,—each her- 
