Rosary pea (Abrus precatorius L.) is the stem and leaf of the legume plant Abrus precatorius L., also known as tu gancao or shan gancao. It is a traditional Chinese medicine with effects such as clearing heat and detoxifying, promoting fluid production, moistening the lungs, and promoting urination. It mainly treats colds, sore and swollen throat, cough due to lung heat, acute mastitis, sores and boils, hepatitis, and so on.
Morphological Characteristics
Abrus precatorius is a climbing shrub. The branches are slender and have appressed short bristles. Even-pinnate compound leaves, alternate, with 8-15 pairs of leaflets, short-stalked, oblong, rounded at both ends, with a very small pointed tip at the apex, 1-2cm long and 0.3-0.3cm wide, hairless above and sparsely appressed fine-haired below. Racemes are very small, 3-6cm long, head-shaped, borne on short branches, without a peduncle, the inflorescence axis short and thick, fleshy. Flowers small, closely arranged, about 9mm long, with short pedicels; calyx yellow-green, bell-shaped, about 3mm long, with 4 short teeth at the apex, hairy on the outside; corolla pale purple, standard petal broadly ovate, with a triangular claw at the base, wings and keel petals narrow; stamens 9, in 1 bundle; ovary superior, hairy; style hairless; stigma with fine papillae. Pod yellow-green, leathery, rhombic-oblong, flat or swollen, 2-4.5cm long, 1.2-1.4cm wide, with a curved beak at the apex, covered with bristle-like fine hairs. Seeds 4-6, elliptical, black at one end of the hilum and vermilion at the upper end, 6.5mm long, glossy. Flowering period March-May, fruiting period September-October.
Ecological Environment
Grows in hilly areas or among thickets in the mountains and along roadsides.
Main Value
[Nature and Flavor] Sweet; cool; non-toxic
[Meridians Entered] Lung; spleen; liver meridians
[Functions and Indications] Clears heat and detoxifies; mainly used for colds, sore and swollen throat, cough due to lung heat, acute mastitis, sores and boils, hepatitis; promotes fluid production, moistens the lungs, clears heat, promotes urination; treats sore throat and bronchitis
[Usage and Dosage] Internal use: decocted in water, 9-15g (3-5 qian). External use: appropriate amount, decocted in water for washing; or fresh product pounded and applied.
[Discussions by Various Authors] 1. "Manual of Raw Herbal Medicines": promotes fluid production, quenches thirst, moistens the lungs, clears heat. Often used as an ingredient for herbal cooling tea.
[Characters] Character identification: the stem is slender, about 1mm in diameter, blue-green; the dried vine stem is thin and lean (those with many leaves and blue-green color are preferred). The surface is covered with sparse bristles; the texture is hard and brittle, easily broken, and the cross-section is hollow. Leaves alternate, even-pinnate compound leaves; leaflets rectangular to rectangular-obovate, oblong. The leaves are pinnate compound leaves, smooth above, and also have sparse fine bristles below, easily falling off. Slight odor, sweet taste. It is the stem and leaf of the legume plant Abrus precatorius.
Microscopic identification: transverse section of the stem: cork layer cells closely arranged, containing brown material; phelloderm parenchyma cells contain numerous calcium oxalate prismatic crystals. The sclerenchyma cell ring of the pericycle has 2-3 rows of cells, and the adjacent parenchyma cells contain relatively many calcium oxalate prismatic crystals. Phloem fibers are arranged radially in bundles, rays 1-4 rows, xylem vessels arranged radially. Pith cells are subrounded, with dotted wall pits on the surface, and the cells also contain calcium oxalate prismatic crystals. Leaf surface view: epidermal cells irregular in shape, cell walls wavy and curved, stomata mainly anomocytic, with 2-7 subsidiary cells. Unicellular non-glandular hairs 144-165(-578)μm long, 13-17μm in diameter, straight, sharply pointed at the apex, smooth on the surface.
[Chemical Composition] The leaves of Abrus precatorius contain abrusoside A, B, C, and D, 5,7,4'-trihydroxyflavane glycoside, 7,4'-dihydroxyflavonol diglycoside, taxifolin(e)-3-glucoside, glycyrrhizin, galactose, arabinose, xylose, abruslactone A, methyl abrusgenate, and abrusgenic acid.