Barleria lupulina
(hophead Philippine violet)

Preferred Common Name

• hophead Philippine violet

Other Scientific Names

• Barleria macrostachya Bojer
• Barleria monostachya Bojer ex Bouton
• Barleria norbertii Benoist

International Common Names

• English: hophead; hophead barleria; hop-headed barleria; snake bush
• Spanish: lengua de culebra

Local Common Names

• Australia: hophead barleria
• Haiti: barré bolé; barré volé; barre voleur
• India: cem-mulli; kanta bishalyakarani; mullu kanagaambaram; semmulli
• Indonesia: landik; sujen trus
• Lesser Antilles: dog bush
• Thailand: phimsen ton; salet phangphong
• Venezuela: lengua de culebra

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Scrophulariales
•                         Family: Acanthaceae
•                             Genus: Barleria
•                                 Species: Barleria lupulina

Acanthaceae is a family of flowering plants comprising about 220 genera and about 4000 species widespread in both New and Old World Tropics (Scotland and Vollesen, 2000; Stevens, 2012). Species within the Acanthaceae includes herbs or woody shrubs, lianas and trees. Barleria (Acanthaceae) is a large, polymorphic, widespread genus of herbs, shrubs and rarely climbers comprising approximately 300 species distributed worldwide (Balkwill and Balkwill, 1998). The greatest representation of this genus occurs in Africa and Asia, with its greatest centre of diversity in tropical East Africa (Balkwill and Balkwill, 1997). The genus Barleria is readily distinguished from other genera in the Acanthaceae by a combination of three features:

(1)  a four-merous calyx with two large outer sepals and two smaller inner ones.

(2)  globose, honey-combed pollen.

(3)  predominance of double cystoliths (calcium oxalate crystals) in the epidermal cells (Balkwill and Balkwill, 1998).

Although each of these features occurs in other Acanthaceae species, their regular co-occurrence is restricted to Barleria (Balkwill and Balkwill, 1997).

The genus name Barleria is derived from the name of a Dominican monk and French botanist, Jacques Barrelier.

B. lupulina is a glabrous, erect and branched shrub, up to 1.5 m tall, with axillary spines; leaves linear-oblong, 3-9.5 cm long, base cuneate, apex obtuse, midrib red above, petiole short, red. Inflorescence a terminal spike with overlapping bracts, up to 9 cm long, bracts broadly ovate, 1.2 cm long, ciliolate, purple tinged, on the back with cupular glands, bracteoles lanceolate, 4 mm long; calyx lobes broadly ovate, pubescent, outer 10 mm long, inner ca 8 mm long; corolla tube 3 cm long, bent at base, expanded above, lobes 5, orange-yellow, stamens 4, didynamous, 2 exserted; longer stamen filaments approximately 2 cm long; shorter stamens fertile. Style approximately 3 cm long, glabrous. Fruit a capsule, ovoid, 2-seeded (Aguilar, 2001; PIER, 2015). 

B. lupulina has been intentionally introduced to be used as an ornamental and as a medicinal herb. In the West Indies, it was probably introduced in the mid-19^th century and it appears in herbarium collections made in 1882 in the US Virgin Islands (St Thomas) and in 1899 in Jamaica (US National Herbarium). 

Soil drainage

• free

Soil reaction

• alkaline
• neutral

Soil texture

• light
• medium

B. lupulina spread by seeds and vegetatively by stem segments. Seeds are spread short distances from the mother-plant when the “explosive” capsules rupture. They are also dispersed by water and by humans as ornamental plantings and in discarded garden refuse (Smith, 2002). 

Once naturalized, B. lupulina grows as a weed and has the potential to outcompete and displace native plants (Aguilar, 2001). The individuals are spiny and therefore hard to control manually. In Australia, B. lupulina is invasive in open woodland habitats and along watercourses in the Northern Territory and was also recently reported as being invasive in Brisbane and in south-eastern Queensland (Weeds of Australia, 2015).

• Proved invasive outside its native range
• Abundant in its native range
• Highly adaptable to different environments
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Highly mobile locally
• Benefits from human association (i.e. it is a human commensal)
• Long lived
• Fast growing
• Gregarious
• Reproduces asexually

• Ecosystem change/ habitat alteration
• Loss of medicinal resources
• Modification of hydrology
• Modification of successional patterns
• Monoculture formation
• Reduced native biodiversity
• Threat to/ loss of native species

• Competition - monopolizing resources
• Competition - smothering
• Hybridization
• Rapid growth
• Rooting
• Produces spines, thorns or burrs

• Highly likely to be transported internationally deliberately
• Difficult to identify/detect in the field

B. lupulina is an attractive ornamental used in gardens, parks and sometime used as a hedge plant (Smith, 1991). It is also cultivated to be used as a medicinal herb. The leaves and roots are chewed against toothache, and a poultice of the leaves is put on bites of insects, snakes or dogs, as an anti-inflammatory (Aguilar, 2001).