Senna is a genus of diverse owering
plants native throughout the tropics.
Four species are native to Florida, and
two — S. ligustrina and S. mexicana
var. chapmanii — are commercially
propagated. Both are great for attracting
pollinators and adding a touch of the
tropics to the home landscape.
Senna mexicana var. chapmanii is known
commonly as Chapman’s wild sensitive
plant, Chapman’s senna and Bahama
senna. It occurs in pine rocklands, coastal
strands and along hammock edges
in only Miami-Dade County and the
Florida Keys. However, it can be planted
in landscapes as far north as Central
Florida. Due to its limited natural range, it
is a state-listed threatened species.
Senna ligustrina, known as Privet wild
sensitive plant or Privet senna, naturally
occurs in coastal counties from Brevard
south on the east coast, and from Gilchrist
and Levy south on the west coast. It can
be found along hammock edges and in
disturbed areas.
Description
With an abundance of showy yellow
owers and gleaming evergreen foliage,
both Privet and Chapman’s senna
make exceptional ornamental plants.
Chapman’s senna is a robust evergreen
perennial that can take on a variety
of shapes — from upright to nearly
prostrate and sprawling. Its owers have
bright, buttery-yellow petals with subtle
red venation. They are born on stalked
clusters in spring and fall.
Privet senna is a fast-growing shrub that
can reach a height of 10 feet or more. It
is lanky, with a thin crown and many short
side branches. If allowed to self-sow, it
may form a dense colony. At maturity,
Privet senna tends to bend under its own
weight. Its owers are lemon yellow. Its
Senna
foliage is similar to that of Chapman’s
senna, with pinnately compound leaves
that are alternately arranged, but its
leaets are linear- to lance-shaped and
more numerous. Overall, its foliage is
less dense. Privet Senna typically blooms
from autumn to late spring but may bloom
sporadically throughout the year.
Planting
Plants are available in 1- and 3-gallon
pots. Both may be used as specimen
shrubs, but Chapman’s senna works best
planted in mass and as a border.
Seeds
Senna seeds usually aren’t available
commercially. Both species are prolic
self-seeders. Seeds typically sprout in
spring.
Plants
Both species are available from native
plant nurseries.
Care
Sennas are not cold tolerant and
may die if exposed to below-freezing
temperatures. Seedlings are slightly more
resilient and may survive. Sennas require
occasional pruning; otherwise, they
can become leggy.
Removal of brown
seed pods will help
the plants remain
attractive when not in
ower and will help
decrease seedlings.
Unwanted seedlings can easily be
removed.
Site conditions
Plant Privet senna and Chapman’s senna
in dry to slightly moist, well-drained soils.
Both can tolerate nutrient-poor soils but
do better with some organic content. Full
sun to light shade is best for both species.
Privet senna can tolerate a little more
shade than Chapman’s — up to half a day
— but neither will ower without several
hours of daily direct sunlight. Despite
being native to coastal areas, Privet senna
is not salt tolerant, although Chapman’s
senna is.
Hardiness zones
Privet senna is suited for zones 9a–11;
Chapman’s senna for zones 10a–11.
Senna owers are visited by sweat,
resin, cuckoo, leafcutter and bumble
bees for their pollen and nectar.
Butteries such as the Sleepy orange,
Little yellow, and Cloudless, Orangebarred
and Statira sulphurs are also
frequent visitors. All members of the
Senna genus are larval host plants for
Sulphur caterpillars.
4–10 ft
Nectar, host
Many non-native
Senna species are
sold commercially. In
particular, Christmas
senna or Buttery senna
(S. pendula) is often
recommended
for buttery gardens. However,
the Florida Exotic Pest Plant Council
(FLEPPC) lists it as a Category I
invasive species, known to alter
native plant communities. It should
be avoided. For more information
on Buttery senna, visit the FLEPPC
website www.eppc.org.
CAUTION
Photo by Melanie Long
Privet senna
Photo by Peg Urban
Cloudless sulphur caterpillar on Privet senna
Photo by Andrea Salas
Chapman’s senna