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Cytisus
scoparius (L.) Link
Standardized Common
Name: Scotch
Broom
Other Common Names: Broom, Irish Tops,
Scoparium
Family: Fabaceae
(Leguminosae)
Taxonomy: Cytisus
includes about 30 species of Old World, mostly Eurasian shrubs. Cytisus
scoparius belongs to Sect. Sarothamnus. It is native to Europe and
is naturalized in the United States. The basionym is Spartium scoparium
L.; other synonyms include Genista scoparia Lam. and Sarothamnus
scoparius (L.) Wimmer ex W. D. J. Koch. Several subspecies may be
recognized, most of which were initially described as species of limited range;
the distinctions among these are not considered important in commerce.
Description: Shrub, to 2 m high;
stems much-branched, erect to procumbent, 5-angled. Leaves alternate,
trifoliolate and petiolate or unifoliolate (reduced to 1 leaflet) and sessile
especially on younger stems, or almost all unifoliolate in subsp. reverchonii;
leaflets 6–20 mm long, 1.5–9 mm broad, elliptic-oblong to obovate, apices
subacute, margins entire; surfaces pubescent or glabrous, lower surface usually
pubescent. Inflorescences racemose; flowers solitary or paired, pedicellate.
Calyx campanulate, bilabiate, upper lip with 2 teeth, lower lip with 3,
glabrous. Corolla yellow, bilaterally symmetrical; standard petal 15–20 mm
long, rounded, with short claw; wings oblong; keel curved, blunt, short-beaked.
Stamens 10, 5 longer, 5 shorter, all filaments attached. Gynoecium
unicarpellate; style convoluted after flowering, ciliate on lower part. Fruit a
legume, 25–40(–70) mm long, flattened, oblong, black, pubescent on margins;
seeds 12–18.
Parts
in Commerce:
Tops harvested at time of flowering, consisting of green twigs
Identification:
- Twigs straight,
branching, tough, flexible, 2–3 mm in diameter
- With 5 very
prominent longitudinal ribs, almost star-shaped in cross-section; ribs not
T-shaped in cross-section
- Epidermis dark
green, sometimes with reddish-brown cork patches
- Hairless or with
soft hairs; apex hairy
- Fracture
fibrous, or tough and splintery in larger stems; fractured surfaces
yellowish
- In
cross-section, contains narrow cortex and pericycle, xylem in unbroken
ring, and large pith; thick-walled fibers concentrated around vascular
cylinder and in ribs
- Taste bitter and
unpleasant
Adulterants: C. scoparius
can be confused with the closely related, yellow-flowered legume Genista
tinctoria L. (Dyer’s Broom, also used in folk medicine). The stems of the
latter are not star-shaped in cross-section. Youngken also reported the
completely unrelated Osyris alba L. as an adulterant; it has numerous
longitudinal striations, and the wood is white.
References:
Fernald ML. Gray’s Manual of Botany, 8th ed. New York: American Book
Company; 1950:890.
Frodin DG, Heywood VH. Cytisus. In: Tutin TG, Heywood VH, Burges NA, et al.,
eds. Flora Europaea. Vol. 2. Cambridge: Cambridge University
Press; 1968:86–90.
Norverto CA, González-Andrés F, Ortiz JM. Leaf and
stem anatomy of species of Cytisophyllum, Cytisus, Chamaecytisus, Genista,
and Genista Sect. Teline (Fabaceae: Genisteae) as an aid for
taxonomy. Israel J Pl Scis. 1994;42:213–225.
Wichtl M, ed. Herbal Drugs and
Phytopharmaceuticals, 3rd English
ed. Stuttgart: medpharm Scientific Publishers and Boca Raton, FL: CRC Press;
2004:555–557.
Youngken HW. Text-Book of Pharmacognosy, 5th ed. Philadelphia, PA: The
Blakiston Company; 1943:467–469.
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