Cestrum parqui Seeds | Willow-leaf Jessamine
LATIN NAME: Cestrum parqui
COMMON NAME: Willow-Leaf Jessamine
Plant Profile
The flowers are tubular, about two centimetres long, and arranged in loose clusters at the ends of the shoots and along the upper stem. Their colour is dull in sunlight and their fragrance barely detectable then, but both are tuned to hawkmoths and other night-flying species,.
The berries and the seed within them carry the same principles as the leaves. That matters both in the field, where seedlings come up in grazed paddocks, and in hay, where dried berries are mixed through the bale and cannot be sorted out. Poultry and cage birds have been poisoned by the fruit.
The berries are eaten by birds, which digest the flesh and pass the hard seed intact, so a single bush in a garden can seed the roadside for a long way in every direction. The seed survives in soil for years, and new plants appear long after the parent has gone.
Cestrum sits in the nightshade family close to the true Solanum species, and a green cestrum in fruit is easily mistaken for one of the shrubby nightshades. The flowers separate it: Solanum flowers have a five-pointed corolla with prominent yellow anthers forming a cone, whereas Cestrum flowers are long narrow tubes with the stamens inside the tube.
The wood is brittle enough that a heavy-handed prune will snap branches rather than cut them, so take out old stems in short sections with a sharp saw rather than trying to bend them aside. Shorten the previous season’s growth in early spring to keep the bush compact and to encourage flowering wood, and thin the centre every few years so light reaches the middle of the plant.
Science & Biotechnology
The poisoning syndrome associated with green cestrum in Australia is liver failure, and it has been traced to a diterpene given the name carboxyparquin, isolated from the plant. The toxin is concentrated in the leaves and remains in the plant after it has been cut and dried, so a paddock cleared of the bush and baled for hay can still kill stock.
Uses & Benefits
Where it is not a declared weed, green cestrum is grown for its evening fragrance, placed near a terrace or under a bedroom window. It should never be planted where livestock graze or where hay is cut, and it should not be planted in bushland or near a watercourse in a region where it is a declared pest.
The plant is toxic on contact with broken skin as much as on ingestion, and the sap stains and irritates. Wear gloves when pruning, and wash the cuttings off your tools and hands before eating. Do not compost the berries where poultry can reach them.
Growing from Seed
Green cestrum is a declared weed in parts of Australia, and it is listed in New Zealand’s national pest plant accord, which makes it illegal to sell, propagate or distribute there. It establishes in disturbed ground, along watercourses and on roadsides, and it tolerates both heavy soil and dry spells.
Sow the cleaned seed on the surface of a gritty, free-draining compost and cover it only lightly, because these seeds want warmth and moisture far more than depth. Keep the pan warm and out of direct sun, and transplant the seedlings as soon as they are large enough to handle, since the roots of nightshade seedlings do not enjoy being confined.
Move seedlings into individual pots when the little plant has reached about the height of the pot rim, and again when it has doubled that, stepping up one pot size at a time. Garden plants are best put out when the stem is about knee high, since smaller plants establish slowly and are the first to be eaten by slugs. Cut back hard in spring if the plant has been frosted.
Our Take
Grow this one for the evening air and for nothing else, and grow it where no stock can reach it. If you want the same nocturnal fragrance without the legal problem, the white-flowered Cestrum nocturnum is the commoner choice in warm gardens, and the angel’s trumpets of Brugmansia suaveolens will scent a courtyard with far bigger flowers. Bitterness of the nightshade kind is also the theme with Solanum dulcamara, worth knowing as the family look-alike.
Related Reading
Gardeners who grow Willow-Leaf Jessamine often pair it with these related subjects: