596 ON THE USE OF POLLEN 
it is with Ficoidee, with ‘which it agrees in little save 
the succulence of its leaves ; yet the last family coincides with 
it in those characters, that in other groups, are considered of 
the highest importance, Crassulacee and Ficoidee, as well as 
Portulacee, Cunoniacee, Baucracee and Fouquieracee, being 
polypetalous dicotyledons, with perigynous exsertion, albu- 
minous seeds, hilose radicles, and central placente : while 
the Rosacee have definite pendulous ovules, and exalbumi- 
nous seeds. The nature of the pollen unites Rosaceae, Sari- 
Jragee and Crassulacee; separating them from the Fi- 
coidee. 
We have many examples among Polypetalous plants, 
demonstrating that the nature of the pollen is superior to the 
exsertion, for the preservation of affinities. Thus, the exser- 
tion separates Ficoidee, Portulacee, and Caryophyllacee, so 
closely connected by their peculiar embryo; the kind of pol- 
len re-unites them. The Rutacee through Hypericinee is 
more closely connected with Myrtacee than it is with Gera- 
niacee or Polygalee: yet the exsertion connects them with 
the latter, and separates them from the former; the pollen, 
however, points out the true affinities. 
e pollen is in Polypetale, sometimes of greater import- 
ance than even the presence of a perianth. "Thus, Sanguisor- 
bee is united to the remaining Rosacee by the characters of 
this organ. 
The resemblance of the pollen, in families whose affinities 
have been long recognized, presents us with further evidence 
of the value of this organ, in this group. Thus, the Gerani- 
acee, Oxalidee, Linee, Balsaminacee, and Tropeolee, all have 
pollen extremely alike. 
e have found some exceptions, however, even in the 
same family. Thus, the pollen of Inga and Acacia is com- 
pound, while that of Papilionacee is simple. Probably the 
same relation may here exist as between Orchidee and Iri- 
dee; or between Boraginee and Monopetalous Dicotyledons 
with definite ovules. In the Ranwnculacee, again, we find 
those genera with follicular fruits having a pollen similar to 
