Apocynaceae
Dogbane Family
By: William McMahan and George Rogers
As traditionally defined, a mostly tropical family of about
300 genera and over 1000 species primarily in tropical regions, with about nine
species indigenous to Florida. This family is prominent in warm-climate
gardening. The plants are usually woody, often shrubs or vines having milky sap,
usually opposite leaves, no stipules, and showy fragrant flowers. The flowers
tend to be funnel-shaped and twisted in the bud, with the twist retained in the
mature flower as a slight twist to the petal. The five stamens have sagittate
(arrowhead-shaped) anthers arranged edge-to-edge in the throat of the tube and
surrounding a swollen stigma. The petals frequently have extra appendages (a
corona). Typically there is one style rising from two separate ovaries (like an
upside-down Y), the ovaries tending to remain separate as paired fruits, these
dry or fleshy. Defining the Apocynaceae
is complicated by an unclear border with the Milkweed Family, the
Asclepiadaceae
(having a specialized flower with the stigmas and stamens combined into a single
unit at the center of the flower, and the pollen grains massed into pollinia).
The two are probably best merged into a single family. We have followed the
traditional separation merely to be consistent with existing horticultural
publications.
Key to Apocynaceae Important in South Florida Landscaping
(with data from BA1)
1. Plants vines…2
1. Plants trees or shrubs…9
2. Stamens and stigma fused into a single unit…Mandeville (Mandevilla species)
2. Stamens and stigma pressed together but not fused…3
3. Flowers white (or pale subdued yellow)…8
3. Flowers bright yellow, reddish, or purple…4
4. Flowers rose-colored, with a corona
(crown of fingerlike projections rising from the flower center)…Rose-Allamanda (Strophanthus
gratus)
4. Flowers with no corona…5
5. Flowers purple; leaves
pubescent…Purple Allamanda (Allamanda violacea)
(Rose Allamanda,
a shrub, is
Strophanthus gratus)
5. Flowers yellow (reddish in some cultivars of
A. cathartica); leaves
glabrous or nearly so…6
6. Leaves opposite, with rounded
tips…Wild-Allamanda (Pentalinon luteum)
6. Leaves whorled, with sharply pointed tips…7
7. Plants aggressive vines, the flowers
2"-5” across, not swollen basally…Yellow Allamanda (Allamanda
cathartica)
7. Plants shrubby, the flowers < 2”
across, swollen basally…Bush Allamanda (Allamanda
schottii)
8. Leaves 2"-4” long, climbing vines; leaf tips acuminate;
flowers white…Confederate-Jasmine (Trachelopermum
jasminoides)
8. Leaves usually < 2” long, mostly
trailing vines used as groundcover; leaf tips acute; flowers near-white with
some yellowish coloration…Small-Leaf Confederate Jasmine (Trachelospermum
asiaticum)
9. Leaves alternate…10 (note three choices for question 10)
9. Leaves opposite or whorled…11
10A. Leaves abruptly narrowed toward the
base…Snow-White Frangipani (Plumeria
pudica)
10B. Leaves linear; flowers with the
yellow tube funnel-shaped; ovules 2/locule; fruit a drupe…Lucky Nut (Thevetia
peruviana)
10C. Leaves elliptic; flowers with the
tube of varied colors (including yellow); ovules several/locule; fruit opening
along one edge...Frangipani (Plumeria
rubra)
11. Leaves whorled…Oleander (Nerium
oleander)
11. Leaves opposite (may be whorled in
Ochrosia)…12
12. Plants with forked thorns…Natal-Plum (Carissa
macrocarpa)
12. Plants thornless…13
13. Shrubs. Flowers pure white with prominent corona (crown at
the center of the petals surrounding the opening into the flower)…Wrightia
13. Plants not with above combination of characteristics…14
14. Leaves long-acuminate at the tips;
flowers white…Pinwheel-Flower (Tabernaemontana
divaricata)
14. Leaves rounded (to short-acuminate) at the tips; flowers
varied in color (including white)…15 (note 3 choices)
15A. Trees or large shrubs; leaves 3"-6”
long; flowers cream-colored; fruit a drupe…Ochrosia (Ochrosia
elliptica)
15B. Small shrubs or subshrubby
perennials; leaves < 3” long; flowers usually rose-colored or white; fruits
resembling small green beans…Rosy Periwinkle (Catharanthus
roseus)
15. Shrub with leaves > 3” long; pink
flowers having a dark eye (flowers similar to those of
Catharanthus)…Pink Kopsia (Kopsia
aculeata)
