John Strother (2007) Xanthium . Flora of North America 21: 19-20

Plants 10–60(–120+) cm tall; nodal spines usually in pairs, simple or with 2–3 lobes, 15–30+ mm long. Leaves: petioles 1–15(–25+) mm; blades ± ovate to lanceolate or lance-linear, 4–8(–12+) long , 1–3(–5+) cm wide, often pinnately 3(–7+)-lobed, lower surfaces gray to white, densely strigose. Burrs 10–12(–15+) mm long. 2n = 36.

This species was discovered in Somaliland after publication of the Flora of Somalia. There are two seeds in each burr. The lower one germinates earlier than the upper one because it has a thicker seedcoat.

Awale & Jama (2018). Hordhaca dhirta badhtamaha Soomaalilaand.

Gu’yaal jire geed gaab ah oo cufan oo aad u laamo badan, oo dherer ahaan 1 m ah, ballac ahaanna 2 m ah. Caleemo inta badan 3 carrab leh oo carrabka dhexe ka ballaadhan yahay kuwa kale, oo gas leh, isla markaana leh aroore si fiican u muuqda. Xagga hoose ee caleentana ku leh 3 laamood oo xooggan oo leh ilko hurdi ah, oo inta badan lammaan. Ubaxu aad uma muuqdo, waa se cagaar xigeen isku beddeleya sidii buro hurdi-bunni ah.  Iniinyuhu waxay ku dhex jiraan buradaas.

Sabo: Dhul cagta lagu badiyey, joog ah 800 – 1500 m.

Filiqsanaan: Asal ahaan ka soo jeeda Koonfurta Maraykanka, imika se ku fidaya dunida oo idil.

Fiiro: Xoolaha ayaa ku sumooba.

Source: Pitcher (2014) with additions by others in 2020.

Why it is Xanthium spinosum is one of the world's worst weeds. It affects many agricultural crops and animal production. Its seeds are easily spread, due to their ability to float and to attach to humans and animals. The plants can quickly become dominant in an area because of their prolific seed production and high germination and survival rates. The presence of two seeds in each bur that differ in their dormany requirements also in­creases its survival chances. It is also toxic, but it is its ability to become dominant in crops, pastures, and disturbed areas that makes it a serious problem,

Xanthium spinosum infestations cause reduced forage production the burs becomes entangled in the wool of sheep and pets. The seeds of Xanthium species are toxic to most domestic animals, particularly swine and horses but, because animals avoid the spiny burs which contain the seeds, they are usually not the cause of Xanthium toxicity. The poisonous compound in Xanthium strumarium (and presumably in X. spinosum), carboxyatractyloside.

Poisoning usually results from eating the stems and leaves of young plants. This often happens at the edges of ponds, lakes, floodplains, or other bodies of water when the water recedes after shallow flooding. Under such conditions seeds germinate readily, constantly supplying new generations of potentially poisonous seedlings as the water source dries out. Animals are attracted to such areas because of their need for drinking water. The problem is made worse by by the natural dormancy of Xanthium seeds. This means they germinate over long periods of time. Ingestion of cotyledons to 0.75 to 1.5 percent of the animal's body weight will cause toxicity.

Toxicity decreases rapidly as true leaves are formed. Evidence of poisoning appears in about 12 to 48 hours, the symptoms being nausea, vomiting, lassitude, depression, weakened muscles, and prostration. Sever poisoning may result in convulsions and spasmodic running movements. Ruminants may not vomit, but death may occur within a few hours or days. Fatty substances such as milk, lard, or linseed oil have been recommended as antidotes. The toxic agent in Xanthium may also be responsible for allelopathic effects.

Control: Mechanical removal prior to flowering is recommended for control. If pulled following flowering, the plants should be burned. Monitoring should be continued on the sites for several years.

Physical removal of the plants by hand pulling or hoeing is effective if done prior to flowering. Since the dormant seed can remain viable for several years, periodic inspection of the area will be necessary, and grubbing may have to be carried out to deal with subsequent germination. Hoed or pulled plants on which the burs are already formed should be removed and burned as the seed can mature even on cut stalks.

Prescribed/controlled burning is also be an effective means of controlling Xanthium, but care must be taken to ensure the burn remains under control. That may be why it is not often used. 

Plants of the World Online (POWO): Xanthium spinosum. The distribution map shows the countries where the taxon is considered native or introduced but is now growing in the wild. 

Global Biodiversity Information Facility (GBIF):  Xanthium spinosum. Records may be of cultivated specimens.