CLASSIFICATION OF THE GENUS ANNONA, WITH DE- 
SORCTEAN OF NEW AND IMPERFECTLY KNOWN 
By W. E. Sarrorp. 
DIVISION OF THE GENUS INTO NATURAL GROUPS. 
INTRODUCTORY NOTES. 
A critical study of the genus Annona has led the writer to place 
the American species in fourteen natural subdivisions or sections. 
These sections, arranged in four groups, are composed of closely 
allied species, in some cases showing their relationship by peculiari- 
ties of leaf structure, in others by the structure of the stamens and 
carpels or form of the flower, and in others by peculiarities of the 
fruit and seed. Some of the sections are more sharply defined than 
others and between several of them there are species which appear 
to be connecting links; but this is equally true of many well-estab- 
lished natural divisions of plants and does not make it less desirable 
to group species in such a manner as to indicate their relationships 
and at the same time to facilitate their study. 
CHARACTERS OF THE GENUS. 
In all species of Annona the leaves are alternate, 2-ranked, entire, 
and devoid of stipules. The flowers may be solitary or geminate, or 
they may be clustered in fascicles of several. They are never axillary 
nor terminal, but are sometimes apparently so by the abortion of an 
axillary branch from the base of which they issue, or that of a ter- 
minal bud, the vestiges of which may be at length almost or entirely 
lost from the growth being directed to the development of the fruit. 
In a few cases, as in the common soursop (Annona muricata), the 
inflorescence is caulifloral, issuing from the old bark of the trunks, 
limbs, or branches. 
The typical Annona flower has a 3-parted calyx, the lobes of which 
are valvate in bud. The corolla is composed of.6 petals in 2 series, 
the inner petals alternating with the outer and consequently opposite 
the sepals or calyx lobes. In all cases the outer petals are valvate, or 
edge to edge. In the type species, Annona muricata (pl. 1), the over- 
lapping inner petals are broadly ovate and somewhat smaller than the 
outer. In other species the inner petals are scarcely larger than the 
HXPLANATION OF PLATE 1.—Field photograph by G. N. Collins, taken in Porto Rico. 
Natural size. 
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