Yellow Cassia (Senna Surattensis): A Tropical Marvel for Your Garden

Senna surattensis, also known as Yellow Cassia, is a shrub or small tree that grows to a height of 5-7 meters. It branches abundantly, with ribbed twigs and a fairly smooth, grey-brown bark.

The leaves are elliptical or ovate, and the undersides are powdery white, covered in sparse, adherent, long soft hairs. The raceme flowers grow in the upper part of the twigs, in the axils of the leaves.

The bracts are ovoid and elongated, externally covered in soft hairs. The sepals are ovate and vary in size. The petals range from bright yellow to deep yellow, and are ovate to inverted ovate, measuring 1.5-2 centimeters in length. The tree has 10 stamens, all of which are fertile.

The pods are flat, strap-like, and dehiscent, with 10-12 lustrous seeds. The flowering and fruiting period is almost year-round. Native to India, Sri Lanka, Indonesia, the Philippines, Australia, and Polynesia, it is cultivated in China’s Guangxi, Guangdong, Fujian, and Taiwan provinces. It has been cultivated worldwide.

Morphological Characteristics

The Yellow Cassia is a shrub or small tree that grows 5-7 meters tall. It branches abundantly, with ribbed twigs. The bark is notably smooth and gray-brown. The young twigs, leaf axis, and petioles are softly hairy.

Leaves are 10-15 centimeters long; leaf axis and petioles are flattened and quadrangular. There are 2-3 club-shaped glandular bodies between the lower 2 or 3 pairs of leaflets on the leaf axis and the upper part of the petiole.

The leaflets come in 7-9 pairs, are elliptical or ovate, measuring 2-5 centimeters in length and 1-1.5 centimeters in width. The undersides are powdery white and covered in sparse, long, soft hairs. The leaflet petioles are 1-1.5 millimeters long and softly hairy. The stipules are linear, curved, about 1 centimeter long, and early deciduous.

The raceme flowers grow in the axils of the leaves on the upper part of the twigs. The bracts are ovoid and elongated, externally covered in soft hairs, and 5-8 millimeters long. The sepals are ovate and vary in size.

The inner ones are 6-8 millimeters long, while the outer ones are 3-4 millimeters long, with 3-5 veins. The petals range from bright yellow to deep yellow, and are ovate to inverted ovate, measuring 1.5-2 centimeters in length.

The tree has 10 stamens; all are fertile, with the lower two having longer filaments. The anthers are elliptical and bifurcated on both sides. The ovaries are linear and hairy.

The pods are flat, strap-like, dehiscent, 7-10 centimeters long and 8-12 millimeters wide. The pods have a slender beak at the top, a neck about 5 millimeters long, and an obvious petiole. The seeds are lustrous and number 10-12. The tree flowers and fruits almost year-round.

Growing Environment

Cultivated in China’s Guangxi, Guangdong, Fujian, Taiwan provinces and other areas. Native to India, Sri Lanka, Indonesia, Philippines, Australia, and Polynesia. Cultivated worldwide.

Habitat

It grows on hillsides and in thickets, and is often used as a street tree. It is commonly seen in villages, along roadsides, or in parks at an elevation of 750-1500 meters. It is widely cultivated in the towns of South China and has become a local landscape tree.

It is neutral to slightly positive, tolerant of shade when young, and prefers full sunlight when mature. It has low requirements for soil, water, and fertilizer conditions, and can grow well on medium-fertility lower hills, gentle slopes, roadsides, and urban green belts.

It can withstand short-term low temperatures of -2°C and general frost, is drought-tolerant but not wind-resistant, and does not tolerate waterlogged areas.

Propagation

Seeding

Seeding can be done in both spring and summer. The fruits ripen throughout the year, turning from yellow-green to yellow-brown or gray-brown when ripe. The fruits do not fall off or split after ripening, and can be harvested throughout the year.

However, the seeds mature and have a higher germination rate from September to November. The seeds are black-brown or yellow-brown and lustrous. The thousand-seed weight is 179, and the germination rate is 40%-60%. The seeds can be stored dry.

Before sowing, soak the seeds in water at a temperature of 40-50℃, and soak for 12 hours after cooling. The ground should be finely prepared for sowing, using the row sowing method, with a row spacing of 25 centimeters, and covering the soil 1 centimeter after sowing.

Seeds sown at the beginning of March begin to germinate about 10 days after sowing, and the entire germination process takes about 20 days. Seedlings should be transplanted before the full expansion of the pinnate leaves.

For 1-6 month old seedlings, it is advisable to apply dilute urea once a month. One-year-old seedlings are 70 centimeters high and 0.7 centimeters in ground diameter. For urban greening, it is necessary to cultivate two-year-old large seedlings after transplantation.

For spring sowing, due to the tight cell layer of the seed coat, the water permeability is poor. Before sowing, soak the seeds in water at a temperature of 85-90 degrees for 24 hours, and repeat the process 1-2 times for the remaining hard grains.

The seeds can be sowed when they swell after absorbing water. Use row sowing with a row distance of 20-25 centimeters, cover the soil thickness of 1.5-2 centimeters, and sow 8-10 kilograms per acre.

Seedlings emerge 7-10 days after sowing, and reasonable density planting should be maintained during the seedling stage to prevent the trunk from bending.

Generally, 6-8 seedlings should be left per meter, and the height of one-year-old seedlings can reach more than 1 meter. Nutrient bowl seedlings can also be transplanted and set in early spring.

The locust sprouts strongly. If large seedlings are cultivated to form a good trunk shape, the trunk can be cut in early spring of the second year, the plant spacing can be increased, and the seedlings can reach 3-4 meters in height in the same year, with straight and robust trunks.

Cuttings

At the end of winter or in early spring, before the leaf buds of the Yellow Cassia sprout, cut the branches of the Yellow Cassia into sections about 20 centimeters long for cuttings. After cutting, pay attention to shading and keep the soil moist.

About two months later, the cuttings of the Yellow Cassia will have rooted and survived. At this time, they can be continuously potted. After potting, place them in a cool place for 1-2 weeks, then gradually move them to a place with plenty of sunlight.

Afterward, the management of the cuttings in the pot is the same as that of the truncation pot method. The growth of Yellow Cassia cuttings is slower than that of truncation pots, so the flowering period is also a month later than that of truncation pots, that is, they bloom in early November.

Root Cutting

At the end of winter or in early spring, cut robust Yellow Cassia roots into sections about 15 centimeters long for cuttings. There is no need for shading, keep the soil moist, and the roots can survive and be potted about a month later. The survival rate is as high as 90%.

The root cutting method of Yellow Cassia not only makes full use and increases the propagation material for cuttings, but also can make Yellow Cassia bonsai according to the different shapes of Yellow Cassia roots, greatly improving the ornamental value of Yellow Cassia potted plants.

When the roots of Yellow Cassia are used as cuttings, their survival rate and growth rate are higher and faster than those of twig cuttings.

Disease and Pest Control

Sudden death disease (vertical pole disease) can be controlled with 800-1000 times the liquid of methyl tobutin or Bordeaux liquid.

Stem rot disease can be controlled by shading in summer, nurturing management without injuring the seedlings, and timely removal of diseased seedlings. It can be sprayed with 800-1000 times the liquid of polyquinoline for prevention and control.

Insect control can be done by manual removal, centralized destruction, or spraying with 800-1000 times the liquid of enemy insects to kill larvae.

Main Value

Ornamental

Yellow Cassia has a beautiful shape and is covered in yellow flowers when in bloom, making it an excellent street tree and stand-alone tree. The tree crown is round, the branches and leaves are lush, the flowering period is long, and the flowers are golden and bright, rich in tropical scenery.

It has now become one of the common street trees and garden landscape trees in various places in South China. It is more suitable to be paired with red flowers and green leaves, making it an important matching flower in gardens.

However, after wind damage, the trunk tilts or breaks, affecting the landscape effect, and needs to be planted in a wind-sheltered place.

The flowers are beautiful and colorful, and can bloom almost all year round, making it an excellent woody flower. It is suitable for planting in gardens and green spaces or as a street tree. It is often used as a hedge and garden ornamental plant for roadside, pond side, or courtyard greening.

Medicinal

Leaves: Cooling and detoxifying, moisturizing the lungs.

Attached prescription:

Properties, tastes, and meridians: Sweet, bitter, cold. Enters the large intestine meridian.

Efficacy and indications: The leaves and seeds of this product can facilitate bowel movements, eliminate stagnation, and guide stagnation. Its seeds can moisturize the intestines and can be used to treat symptoms of intestinal dryness and constipation. Small amounts are used for mild laxatives, large amounts for purgatives.

Dosage: Oral administration: Decoction, 3-10 grams, leaves can be used to make tea.

Various theories: “New Hua Herbal Compendium”: “The leaves and seeds have a laxative effect.”