Plants With Spiny Seedpods & Flowers. Curious nature lovers regularly find unusual plants poking up in their own yards or those of their friends and family. A striking vegetative combination like spiny seedpods and flowers is bound to get the attention of an onlooker. Whether you’d like to add more of your … Thorn apple is a weed that prefers a warmer climate than Britain, but in hot summers they are quite commonly found. Another common name, devil's snare, sounds alarming, but a few simple precautions will enable gardeners to handle this weed without great risk. Appreciate this witchy weed’s beautiful blooms and spiky seedpods, but beware. Its notoriously toxic seeds and leaves can cause convulsions, hallucinations or even death, and climate change is making its poisons even more powerful.
Plants With Spiny Seedpods & Flowers
Curious nature lovers regularly find unusual plants poking up in their own yards or those of their friends and family. A striking vegetative combination like spiny seedpods and flowers is bound to get the attention of an onlooker. Whether you’d like to add more of your newfound plant to the landscape or obliterate it completely, it helps to know what kind of plant you’re dealing with. Several plants sport spiny seedpods and flowers.
Datura innoxia and Datura stramonium are both ornamental plants that grow in Sunset’s Climate Zones 8, 9 and 11 through 31. These 3- to 6-foot-tall perennials boast large, trumpet-shaped flowers and spiny seedpods. Daturas are night-bloomers that release a perfume into the moonlit garden when planted as part of a landscape. Sometimes confused with moonflower, Daturas are in no way related. Datura is a bushy plant related to imsonweed, where moonflower is a climbing vine related to the sweet potato and morning glory. Many Datura plants are poisonous, so take caution in selecting their permanent locations.
Castor Oil Plant
The most dominant feature of castor oil plant (Ricinus communis) is the mass of round, spiny seedpods that erupt after its white stalk-borne flowers begin to fade. In Sunset’s Climate Zones 23 through 28, H1 and H2, it can overwinter and grow into an impressive treelike plant. The rest of the country enjoys the unmistakable castor oil plant’s large lobed foliage during the growing season and sacrifice it to the winter, treating it as an annual in plantings. This plant’s seeds are the source of castor oil, although it is not recommended that you attempt to press your own.
Wild cucumber (Marah macrocarpus) is a beautiful native plant related to gourds, squash, cucumbers and melons. This perennial vine emerges yearly from a massive fleshy tuber and scrambles rapidly before setting delicate, white fuzzy flowers in clusters. The 4-inch-long, egg-shaped seedpod hardens into a spiny fruit containing several black seeds. Although once used as marbles and jewelry by Native Americans, the seeds are bitter and poisonous.
Prickly poppy (Argemone mexicana) thrives with abuse and reseeds itself readily when given the opportunity. The only parts of this 3-foot-tall poppy that aren’t covered in spines or sharp edges are the 1 1/4-inch-wide yellow flowers. Although treacherous, this poppy is often grown in Sunset’s Climate Zones 7 through 43, 2A, 2B, 3A, 3B, H1 and H2. The seeds germinate readily, often when one of the spiny seedpods drops to the ground and shatters.
Other plants with spiny seedpods and flowers that grow wild could be either puncturevine (Triblus terrestis) or California burclover (Medicago polymorpha). Both are considered weedy plants in many Western states. Puncturevine is mat-forming weed with small, oval-shaped leaves on long stems that generally lie along the ground. It sports small yellow flowers and produces razor sharp, spiny seedpods that can puncture bicycle tires. California burclover is a member of the pea family and strongly resembles white clover. However, its three-part leaf is made of three small leaflets, each held on its own short stem. California burclover can grow up to about 2 feet, but generally lies along the ground. Flowers are small and yellow, eventually giving way to seedpods with two or three rows of prickly hooks.
Datura stramonium (thorn apple)
Thorn apple is a weed that prefers a warmer climate than Britain, but in hot summers they are quite commonly found. Another common name, devil’s snare, sounds alarming, but a few simple precautions will enable gardeners to handle this weed without great risk.
Latin name Datura stramonium
Common name Thorn apple
Life cycle Annual
Areas affected Uncultivated ground, beds, borders
What is Datura stramomium
Datura stramonium (or thorn apple as it is commonly known) is an annual weed of gardens, roadsides and other waste or cultivated land. It is widely naturalised in warmer countries throughout the world, and is quite common in the British Isles, often appearing in waste and cultivated ground.
Although quite a striking plant, it is as well to be aware that all parts, particularly the seeds, are highly poisonous. It belongs to Solanaceae, a family which includes the potato and tobacco, and many members of this family contain toxic substances. This page looks at options for gardeners when Datura stramonium is becoming a problem.
This weed can grow to heights of 1m (3¼ft). It flowers from July to October with wide, funnel-shaped flowers. These are usually white but plants with purple or lilac flowers and purplish stems are referred to as Datura stramonium var. chalybaea (syn. D. stramonium var. tatula).
It produces seedpods which are large and spiny (hence the common name thorn apple) though plants with spineless seedpods are known and these are referred to as D. stramonium var. inermis.
The leaves very broad and coarsely toothed.
The potentially harmful poisonous and hallucinogenic properties of this plant can sound alarming especially when made much of in the media. The leaves and seed pods also look exotic and alien. In fact this is quite a small plant and not very invasive in Britain. Common sense precautions limit risk factors so that gardeners need not be too alarmed by this weed.
The seed appears to retain its viability for many years when buried and germinates when the soil is disturbed. Spread is facilitated by human activities – in gardens it appears to be a contaminant of birdseed.
The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.
There are a number of non-chemical control options.
Dig, pull or hoe out plants before seed is set. Seedlings and plants that have not set seed can be added to the compost heap where the toxins will naturally break down. However, plants that have set seed should be consigned to the green waste collection, buried deeply (60cm/2ft or more) or burnt in order that the seed does not disperse in the garden or persist in the compost heap. Always wear gloves or thoroughly wash hands after handling this plant.
Use a mulch of organic matter, at least 5cm (2in) thick or opaque sheeting, such as woven polypropylene, to smother this weed.
Contact herbicides such as acetic acid (eg. Weedol Gun! Fast Acting, Roundup Speed Ultra, Spot On Fast Acting Weedkiller or Resolva Fast Weedkiller), fatty acids (eg. Job Done Garden Ultrafast Weedkiller) and pelargonic acid (eg. Doff 24/7 Fast Acting Weedkiller, Roundup NL Weed Control or Resolva Xpress Weedkiller) are good at knocking back young annual weeds such as thorn apple. Systemic herbicides such as glyphosate (e.g. Roundup Fast Action, SBM Job done General Purpose Weedkiller or Doff Advanced Concentrated Weedkiller) will also be effective and can be used when mature plants need to be eliminated.
These herbicides are non-selective and so care should be taken while spraying near other plants. Plants to be avoided can be covered with a bucket/flowerpot or screened with plastic when spraying.
Inclusion of a weedkiller product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener.
Weedkillers for gardeners (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 3a and 4)
Weed of the Month: Jimson Weed
Jimson weed (Datura stramonium) is a beautiful, witchy plant that begins blooming in late summer and continues through the first frost. A member of the notorious nightshade family, its more famous cousins include tomato, eggplant, pepper, tobacco, and potato. Most members of this plant family are poisonous, and jimson weed is no exception. All parts of the plant are toxic, most particularly the seeds. Potent amounts of alkaloid compounds are present, which potentially cause convulsions, hallucinations, and even death if ingested. And as climate change increases the amount of carbon dioxide in the air, studies have found that the toxicity of plants like jimson weed only increases.
The genus name Datura comes from the Hindi word for the plant, noteworthy since most botanical names are derived from Latin or Greek. The origins of the plant itself are contested—every source I checked listed a different native origin, ranging from Mexico to India, and it now grows all over the world. Not surprisingly, it has found its way into many cultural and medicinal traditions. Ayurveda, traditional Chinese medicine, and Native American shamanistic practices all employ jimson weed medicinally or ritualistically. Its seeds and leaves are used as an antiasthmatic, antispasmodic, hypnotic, and narcotic.
Having grown up in Virginia, I was intrigued by one of the common names I saw recurring in my plant books—Jamestown weed—and researched the origins. One story simply connects the first New World observations of the plant to settlers in this early Virginia colony. A more famous tale tells of the plant’s accidental ingestion by some British soldiers sent there to suppress Bacon’s Rebellion in 1676. After eating some in a stew, the soldiers spent 11 days in a hallucinatory stupor, blowing feathers, kissing and pawing their companions, and making faces and grinning “like monkey[s].”
Jimson weed’s white to purple blooms are fragrant at night, attracting moths and other nocturnal pollinators, a common trait in white-bloomed plants. The rest of the plant, however, is stinky! Crush and sniff the oaklike leaves, and you’ll understand why domesticated and wild animals avoid eating this plant—it smells a bit like feet. Indeed, accidental poisonings tend be more common among humans than among other animals.
Though the trumpet-shaped flowers are stunning, my favorite part of the plant is the devilish-looking seedpod. The size of a Ping-Pong ball and covered in spikes, the seed capsule splits into four parts like a monster’s maw, revealing the dark brown seeds inside. In the winter you might notice its tall, dry stalks bearing the prickly seedpods, which to me look like the scepter for a demon. With all its extraordinary looks and lore, jimson weed is a fascinating plant to contemplate (but maybe not cultivate)!
The Weed of the Month series explores the ecology and history of the common wild plants that most gardeners consider weeds.
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Saara Nafici is the executive director of Added Value/Red Hook Community Farm. She is also the former coordinator of the Garden Apprentice Program at Brooklyn Botanic Garden and a longtime activist, feminist, bicyclist, naturalist, and youth educator. Follow her weedy plant adventures on Instagram.