Reproductive biology of Deeringothamnus rugelii and D. pulchellus (Annonaceae)

The genus Deeringothamnus (Annonaceae) comprises two species, D. pulchellus Small and D. rugelii (B. L. Rob.) Small; both are endemic to Florida, and federally listed as endangered. Field observations and experiments in central Florida determined their phenology, pollination, breeding system and germination. The species are protogynous, although there is an overlap of female and male stages in both. They are similar in floral morphology but differ in color and scent. They differ from Asimina in their small flowers with subequal petals and low number of stamens (16‐34) with elongated connectives. They are both spring‐flowering shrubs, but anthesis begins four to five weeks earlier in D. pulchellus . Fire or other disturbances enhances flowering dramatically. Pollinators are few and infrequent and may include flies, tumbling beetles, and thrips. Hand‐pollination (self) resulted in 4.4% fruit set vs. 19.5‐23.5% in hand‐pollination (cross) and 1.6‐1.8 % in open‐pollinated flowers of D. rugelii . Open‐pollinated flowers of D. pulchellus yielded 1.2% fruit set and 11.4% when they were hand‐pollinated (cross). Over a six‐year period, 80.5% of open‐pollinated seeds of D. rugelii germinated and survived, vs. 42.6% in hand cross‐pollinated and 34.8 % in hand self‐pollinated. Two instances of natural intergeneric hybrids are described: A. pygmaea × D. rugelii and A. reticulata × D. pulchellus .