Reproductive cycles of Juniperus oxycedrus subsp. oxycedrus and subsp. macr
ocarpa were studied during three consecutive years in southwestern Spain. T
he two subspecies showed two-year reproductive cycles in which all the even
ts were similar and synchronous. Pollen was dispersed in late October to ea
rly November. Seed cones began to secrete pollination drops in late October
: unpollinated ovules secreted until February. Cones in which no ovule was
pollinated aborted. Pollen grains germinated in early February. Fertilisati
on took place at the end of May or beginning of June, and seventeen months
later, the embryo was completely mature. Unpollinated ovules failed to matu
re. Some pollinated ovules aborted in late January, probably as a consequen
ce of a failure in megaspore development. Many others aborted at the mature
gametophyte stage, just at fertilisation time. Results are dicussed in rel
ation to deficient pollination and low pollen viability or vigour.