Common Name: Indian Hemp

General Information

Apocynum cannabinum is an erect, herbaceous, perennial plant producing branched stems 30 - 180cm tall from a rapidly spreading, rhizomatous rootstock[].
Indian hemp was much used by the native N. Americans, for whom it was a medicine chest as well as a source of a latex and an excellent fibre. It is still sometimes used for these purposes.
The plant is listed as a noxious weed in parts of N. America[].

Known Hazards

All parts of the plant are poisonous, though various reports differ, with some saying concentrations are low, whilst others say it is high[, , , , , ]. It contains the toxic cardioactive glycoside cymarin[].
The plant is poisonous to all livestock, although domestic sheep are affected most. However, actual cases of livestock poisoning are rare[].

Botanical References

,

Range

N. America - British Colombia and Northwest Territories to New Brunswick, south to California, Texas and Florida

Habitat

Gravelly or sandy soil, mainly near streams[]. A common weed of cultivated land[], usually found in shady or moist places[].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Perennial
Height	0.60 m
Pollinators	Bees, Lepidoptera
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

A plant of the temperate zone, where it is found at elevations up to 2,000 metres. It grows best in areas where annual daytime temperatures are within the range 12 - 22°c, but can tolerate 6 - 30°c[]. When dormant, the plant can survive temperatures down to about -35°c, but young growth can be severely damaged at 0°c[]. It prefers a mean annual rainfall in the range 600 - 1,200mm, but tolerates 150 - 1,500mm[].
An easily grown plant, it prefers a sandy soil but will succeed in sun or quite deep shade in most well-drained moist soils[, , ]. Prefers a pH in the range 5 - 7, tolerating 4.5 - 8[].
Plants spread freely at the roots, often producing new shoots at a considerable distance from the main clump, and can be invasive[, ].
Although the flowers are visited by a wide range of bees, wasps, flies, lepidoptera and other insects who feed on the nectar, it appears that these visits do not succeed in pollination. Successful transfer of pollen seems to occur only when the insect is trapped in the flower and struggles to escape, in turn collecting pollen[]
The young shoots of this plant are extremely attractive to slugs[].
Although top-growth is killed by fire, the rootstock usually survives and resprouts freely[].
Hybridization is common within the genus Apocynum. This species commonly hybridizes with Apocynum androsaemifolium to produce Apocynum × medium Greene[].

Edible Uses

Seed - raw or cooked[]. It can be ground into a powder and used as a meal[].

A latex obtained from the plant is used as a chewing gum[, , ]. After the latex has been squeezed from the plant it s allowed to stand overnight to harden into a white gum[]. The latex was sometimes mixed with clean clay[]. Some caution should be exercised in this use - see the notes above on toxicity.

Medicinal

Indian hemp is an unpleasantly bitter stimulant irritant herb that acts on the heart, respiratory and urinary systems, and also on the uterus[]. It was much employed by various native North American tribes who used it to treat a wide variety of complaints including rheumatism, coughs, pox, whooping cough, asthma, internal parasites, diarrhoea and also to increase milk flow in lactating mothers[].
The plant is still used in modern herbalism, but it should be used with great caution, and only under the supervision of a qualified practitioner if taken internally[[, , ]. See the notes above on toxicity[, ].

The root is cardiotonic, diaphoretic, diuretic, emetic and expectorant[, , , , ]. It is harvested in the autumn and dried for later use[]. The fresh root is the most active part medicinally. It has been used in the treatment of syphilis and as a tonic[]. A weak tea made from the dried root has been used for cardiac diseases[, ].
A tea made from the root has been used as a vermifuge[].

The milky sap, applied topically, is a folk remedy for venereal warts[].

The plant is used in homeopathy[]. It is said to be an efficient remedy in the treatment of dropsy, ascites, anasarca and hydrothorax, and urinary troubles, especially suppression and strangury. It is also said to be of value in the digestive complaints of Bright's disease, with the nausea, vomiting, drowsiness and difficult breathing[].

Agroforestry Uses:

The flowers are attractive to bees[].

Other Uses

A very good quality fibre obtained from the bark is used for making clothes, twine, bags, linen, paper etc[, , , , , , , ]. It is about 12 - 18mm long[]. Very strong[], it is used as a flax substitute[], it does not shrink and it retains its strength in water[]. The fibre is produced late in the season[], it can be harvested after the leaves fall in autumn but is probably at its best as the seed pods are forming[]. When making paper, the stems can be retted by leaving them in the ground until they are dry in the winter or they can be harvested in late summer, the leaves removed and the stems steamed to remove the fibre[]. The stems are then cooked for two hours with lye and pounded with mallets[].

A thick milky, poisonous latex exudes from any broken portion of the plant[]. This latex is a possible source of rubber[, , ]. The latex is also used as a chewing gum.

Propagation

Seed - best sown as soon as it is ripe in late summer and overwintered outdoors. The seed requires a period of cold stratification if it is to germinate well[]. Stored seed germinates better with no cold stratification, best germination rates occurred at 35°c[]. Prick out the seedlings when large enough to handle and grow them on in a cold frame for their first winter, planting out in late spring of the following year[].
The seed has a fairly short viability, rarely lasting longer than 12 months in nature[1050.
Division in spring just before active growth begins[]. Plants can also be divided in the autumn[].