P. pyriferum

from The Collaborative International Dictionary of English v.0.48

Guava \Gua"va\, n. [Sp. guayaba the guava fruit, guayabo the
   guava tree; prob. fr. the native West Indian name.]
   A tropical tree, or its fruit, of the genus {Psidium}. Two
   varieties are well known, the {P. pyriferum}, or {white
   guava}, and {P. pomiferum}, or {red guava}. The fruit or
   berry is shaped like a pomegranate, but is much smaller. It
   is somewhat astringent, but makes a delicious jelly.
   [1913 Webster]