The Genus Senna
Family: Fabaceae
This diverse genus is native throughout the tropics, with a small number of species in temperate regions and consists of about 302 species at the time of writing this entry. They range from being small perennial plants to tropical trees. There are 14 species in Arizona. Many species of Senna were formerly known as a Cassia species.
We are interested in the native species of Senna here. In recent decades, the Australian sennas have become popular. They make nice shrubs, but compared to the native species of Senna which are larval hosts for numerous butterflies, and service all sorts of native bees, the Australian Sennas only seem to attract domestic (non-native) bees. They are also starting to become invasive, escaping cultivation and showing up in the desert.
The native sennas are interesting not only as wildlife plants, but have interesting chemistry. they have been studied for their beneficial effects arising from the abundance of phytochemicals, bioactive components and antioxidant and antimicrobial properties.
Photo of Senna covesii by Liz Makings, SEINET
Senna alata
Candelabra Bush
This is a tropical plant which in frost-free locations can become a 12’ tree. Most often in our region this is a tall-growing bush which freezes back in winter, growing back from the roots much like bird of paradise (Caesalpinia pulcherrima) or a Bouganvilla. In summer it blooms with bizzare flower spikes of yellow flowers that give it the name “candelabra”—the inflorescence looks like melted candles. Winged seed pods follow the flowers. Like with all sennas, this species has intensely aromatic foliage.
Plant in full to part sun, best against a south or west-facing wall where it can find protection in winter. Cut back to manage its size, and encourage bushiness, or let it grow tall and tree-like, whatever your preference is. Plants take moderate water when established. Plants are damaged in the upper 20s°F but are root hardy to at least the low 20s. You might wrap the base of the plant in winter if it gets colder.
Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana).
This species is often called the ringworm bush where it grows (and in various languages) because of its very effective fungicidal properties, for treating ringworm and other fungal infections of the skin. The leaves are ground in a mortar to obtain a kind of "green cotton wool". This is mixed with the same amount of vegetable oil and rubbed on the affected area two or three times a day. A fresh preparation is made every day. Its active ingredients include the yellow chrysophanic acid. Its laxative effect, due to its anthraquinone content, is also well proven. This species has been introduced all over the tropics and subtropics of the world, and everywhere it has been introduced, it is used medicinally.
Formerly known as Cassia alata. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants. The species alata means wing-like fruits.
This species is native to most of the Neotropics (from Mexico and the West Indies to Paraguay), and can be found in diverse habitats. It has become an invasive species in Africa, Asia, and Pacific Islands.
Senna armata
Spiny Senna
Spiny shrub growing about 4’ high and 6’ wide. Bright yellow flowers in spring into early summer. The spiny branches are coated in tubular hairs which help protect it from hot desert air. The fruit is a cylindrical pod, a little over 3/4" long, which falls off and contains a few seeds.
Full sun, moderate to low water with very well drained soil, cold hardy down to 15°F. Don’t water too much during the summer.
Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana).
The medicinal use of this plant is not well-documented but probably has similar chemistry and potential.
Formerly known as Cassia armata. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants; the species epitaph, armata, means armed, referring to the spinescent nature of the plant.
Sandy or gravelly washes below 3200 ft. in California, Nevada, Arizona, and Baja California.
Senna bauhinioides
Twin-Leaf Senna
Small shrub only growing a little over a foot high and wide. Yellow flowers appear in spring through summer. Flowers are followed by small legume pods full of small seeds.
Full sun, moderate water. Temperatures below 25°F will see twin leaf senna freezing to the ground but the plant is root hardy to 0°F.
Plant is eaten by Sonoran Desert tortoises. Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana). Formerly known as Cassia bauhinioides.
The medicinal use of this plant is not well-documented but it most certainly has similar chemistry to other plants more well-known as medicine.
Formerly known as Cassia bauhinioides. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants; bauhinioides means resembling the genus Bauhinia, which also has leaflets in pairs.
Found on gravelly flats and plains, along washes, and rocky slopes, from 2,000-5,500 ft. in Arizona, New Mexico, Texas, and south into northern Mexico.
Senna covesii
Desert Senna
Small subshrub growing to about 1.5’ high x 2’ wide. Popcorn-yellow flowers appear in warm weather. Reseeds readily. This is the most common
Grow in full to reflected sun, low water, hardy to 20° F.
Desert tortoises love to eat this plant. Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana).
This species has similar chemistry to well-known medicinal plants and can probably be used in very similar ways.
Formerly known as Cassia covesii. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants, while covesii is named for Elliot Coues (1842-1899) an American naturalist who is best known for his ornithological work.
Found on flats and along washes, in gravelly and rocky soils from 1,000-3,000 ft. in southern California, southern Nevada, Arizona, southern New Mexico, into northern Mexico.
Senna hirsuta var. glaberrima
Slimpod Senna
Herbaceous shrub, growing 4x4’. May freeze to ground in winter (dormancy) but reemerges quickly in spring. Yellow popcorn flowers appear in warm weather followed by long, skinny pods full of seeds. Plants readily reseed in the landscape.
Grow in full to part sun, moderate water, root hardy to probably 10°F or colder, judging by their natural distribution.
Desert tortoises love the flowers and leaves of this plant. Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana). Formerly known as Senna leptocarpa or Cassia leptocarpa.
This plant must have been used medicinally but it is not well-documented.
This plant was formerly known as Cassia leptocarpa or Cassia gooddingii. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants, while hirsuta means covered with hair.
Found along streams and washes, in disturbed areas and roadsides, from 2,500-5,000 ft. in southern Arizona, southern New Mexico; south to South America; also in Africa, Australia and Asia.
There are three varieties of this species:
Senna hirsuta var. glaberrima, Woolly Senna (AZ, NM only)
Senna hirsuta var. hirsuta, Woolly Senna
Senna hirsuta var. leptocarpa
There is very little information, published or on-line, available for this species in general and especially variety "hirsuta". And there have been many name changes that further confuses the issue. But the variety glaberrima is the one you will find in Arizona.
Senna lindheimeriana
Velvet Senna
This is an herbaceous, usually deciduous (though in many parts of our area, evergreen), velvety shrub growing about 4’ tall x 3’ wide. Yellow flowers from June until the end of fall followed by small legume pods full of seeds. Plants reseed in the landscape readily.
Grow in full to part sun, moderate water—ensure good drainage, hardy to at least 20° F.
Desert tortoises eat the plant and flowers. Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana). Formerly known as Cassia lindheimeriana.
Medicinal use is not documented but this species can probably be used like other species of Senna.
Formerly known as Cassia lindheimeriana. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants, and lindheimeriana is named after Ferdinand Jakob Lindheimer (1801-1879) a German Texan botanist who spent his working life on the American frontier.
Found on dry mesas and in foothills, from 4,500-5,500 ft. in southeast Arizona, New Mexico, and Texas, south into northern Mexico.
Senna occidentalis
Coffee Senna
This is an herbaceous, shrubby plant that reaches 3-6’ tall. Popcorn yellow flowers appear in warm weather followed by slim legume pods full of seeds.
Grow in full to part sun, moderate water
Desert tortoises eat the plant and flowers. Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana). Formerly known as Cassia lindheimeriana.
This species is used as a coffee substitute in spite of the fact that the seeds are reported to be toxic to cattle. It has medicinal and insect repelling properties.
Formerly known as Cassia occidentalis. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants. The species “occidentalis” means western, referring to the relative distribution of the plant to some other species of Senna.
Found throughout southern United States of America, Mexico and South America. In many parts of the world this species has been introduced, and everywhere it is introduced, it is used as medicine.
Senna pallida
Twin-Flowered Senna
Deciduous shrub growing to about 5’ high and wide. Yellow flowers that emerge in pairs through the cool season, starting in fall, and can last until about April.
Full to part sun, moderate water, foliage and new twigs damaged at 15°F, but root hardy to about 0°F.
Plants and flowers are eaten by Sonoran Desert tortoises. Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana).
Formerly known as Cassia biflora. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants. The species, pallida, translates to “pale”—the botanist that named this plant must have found it pale in comparison with other plants.
Moist or dry, usually brushy plains and hillsides, often in pine-oak forest, usually at low elevations but also ascending to 6000 ft. from Sonora, south throughout Mexico.
Senna polyantha
Goldman’s Senna
Large, upright, semi-deciduous shrub growing to about 10’ tall, though often seen much smaller. Can sometimes take on a treelike shape in frost free areas. Yellow flowers in summer into fall, followed by segmented pods.
Full to part sun, moderate water, hardy to about 28°F.
Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana).
Medicinal use undocumented.
Formerly Senna goldmanii or Cassia goldmanii. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants. The species name, polyantha, is from a Greek term meaning many flowers.
Native to Baja California and a few other scattered locations throughout Mexico in canyons and slopes.
Senna purpusii
Baja Senna
Mostly evergreen shrub with distinct, almost succulent, blue-green foliage. Growing about 5x5’ in frost free areas. Yellow flowers appear from April into summer.
Full sun, low water with good drainage, hardy to about 28°F. This species is prone to overwatering so be careful to ensure good drainage and be careful, especially when getting them established.
Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana).
Formerly known as Cassia purpusii. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants. The species epithet “purpusii” (purpus'ii:) is named in honor of Carl Albert Purpus, (1851-1941) (aka Carlos Alberto).
Ethnobotanical use undocumented. This plant is very rare in the trade but is surprisingly found in some nurseries that specialize in rare succulents and caudiciforms.
Coastal mesas, plains, and along arroyos, sandy-gravelly flats near Creosote bush scrub in Baja California.
Senna roemeriana
Two-Leafed Senna
An herbaceous perennial, usually deciduous, reaching about 1-2’ tall and wide. Yellow flowers appear in warm weather followed by seedpods. This species closely resembles Senna bauhinioides but has pointier leaves.
Desert tortoises eat the plants. Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana).
Ethnobotanical uses undocumented.
Formerly known as Cassia roemeriana. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants. The species epithet honors German geologist Ferdinand von Roemer, who lived in Texas from 1845 to 1847 and became known as the "father of Texas geology".
Native to grasslands and open woodlands, often on limestone soils, in New Mexico, Texas, and Oklahoma and in adjacent northeastern Mexico into Nuevo Leon.
Senna wislizenii
Shrubby Senna
Deciduous shrub growing to about 6’ tall and up to 8’ wide. Yellow flowers in summer followed by slender seed pods full of small seeds. Much woodier than most sennas.
Full to part sun, moderate water, hardy down to at least 10°F.
Flowers are nectar rich and visited by many butterflies, bees, and more. Butterfly larval plant for the Sleepy Orange (Abaeis nicippe), Cloudless Sulphur (Phoebis sennae), southern dogface (Zerene cesonia), Mexican Yellow (Eurema mexicana), Boisduval's Yellow (Eurema boisduvaliana), and moth larval plant for the Genista Caterpillar (Uresiphita reversalis), Salt Marsh Moth or Acrea Moth (Estigmene acrea), and the Black-tipped Rudenia Moth (Rudenia leguminana).
The ethnobotany of this plant is mostly undocumented.
Formerly known as Cassia wislizeni. The genus epitaph, Senna, is derived from the Arabic name "sana", which refers to the name of plants found in that region; the same word referring to the medicine made from such plants. The specific epithet is named after Dr. F. A. Wislizenus, a botanist who studied Mexican flora in the mid-19th century.
Chihuahuan scrub and desert grasslands on plains, dry slopes and mesas; 3608 - 5577 ft. in southeastern Arizona, southwestern New Mexico, southwestern Texas; south into central Mexico.