Gen info
- Hoya is a genus of over 500 species of plants in the dogbane family, Apocynaceae, commonly known as wax flowers. Plants in the genus are mostly epiphytic or lithophytic vines, rarely subshrubs. (9)
- Taxonomy: The genus was first formally described in 1810 by botanist Robert Brown in his book Prodromus Florae Novae Hollandiae et Insulae Van Diemen, and honors Thomas Hoy, the gardener for the Duke of Northumberland. The first species of Hoya that Brown described, the type species, was Hoya carnosa. (9)
- Hoya diversifolia is a widespread species of flowering plant in the family Apocynaceae.
- Study reports on the presence of 39 species and six subspecies of Hoyas in the Quezon province. Among the species, 37 are reported as endemic and two as indigenous. It is suggested, Quezon province houses a higher number of Hoya species than other places in the Philippines. Most of the Hoyas listed are epiphytic, thriving in forests ranging from low to 650 m above sea level. (8)

Botany
• A climber with branches up to 4 m long; leaves broadly ovate to obovate-oblong, up to 14 cm × 5 cm, fleshy, petiole up to 1.5 cm long; flowers 9-14 mm in diameter, corolla pale outside, tinged with violet and densely appressed white-hairy inside, shallowly lobed, lobes with recurved top; follicle lanceolate, c. 13 cm long. (PROSEA)

Distribution
- Native to the Philippines. (1)
- Also native to Andaman Is., Borneo, Cambodia, Hainan, Jawa, Laos, Lesser Sunda Is., Malaya, Myanmar, Sulawesi, Sumatera, Thailand, Vietnam. (1)
- Occurs an epiphyte or terrestrial in open forest, but also on wayside trees, up to 400 m altitude.
- Usually found climbing on and even covering trees in shoreline mangrove forests, and further inland.  (4)

Constituents
- Study of dichloromethane extracts isolated ß-amyrin cinnamate (1), squalene (2), ß-sitosterol (3), a mixture of ß-amyrin (4a) and α-amyrin (4b) and lupeol (4c) in a 4:2:1 ration and saturated hydrocarbons from leaves, taraxerol (5), lupeol cinnamate (6), and a mixture of 3 and stigmasterol (7) in a 2:1 ratio from stems. (7)

Properties
- Study suggested antibacterial properties.

Parts used
- Leaves, flowers, latex.

Uses
Edibility
- Conflicting information on edibility: Latex reportedly used to stimulate digestion. There are some reports that the sap is mildly toxic, and caution is advised on ingestion of other plant parts, especially leaves and stems.
- While the flowers are not typically consumed, the nectar is reportedly edible: thick, orange, with a sugary, honey-like flavor. If tempted to taste the nectar, make sure the plant has not been treated with pesticides.
Folkloric
- In Peninsular Malaysia and Vietnam, decoction of leaves used as bath for treatment of rheumatism. (3)
- Latex reportedly poisonous. In Malaysia, used to ease painful catfish stings. for treatment of cough, and in hot baths, for rheumatism.
- Flowers applied to relieve pain of rheumatism. Also used as anti-nematodal against Bursaphelenchus xylophilus. Plant also used for treatment of skin diseases such as eczema, abscess, acne, boils, scabies, itching, sores, rashes, scars, and warts. (6)

Studies
• Antibacterial / Leaves: Study of evaluated the antibacterial properties of ethanolic extract of H. diversifolia leaves extract using disc diffusion assay against several Gram negative and Gram positive bacteria. The extract exhibited inhibition of growth of methicillin-resistant Staphylococcus aureus, Escherichia coli, and Bacillus cereus, with MICs of 25mg, 25 mg, and 100 mg/ML respectively at 24 and 48 hours incubation period. (6)

Availability
- Wild-crafted.
- Plants in the cybermarket.

Additional Sources and Suggested Readings
(1)
Hoya diversifolia / KEW: Plants of the World Online
(2)
Apocynaceae: Hoya diversifolia / Co's Digital Flora of the Philippines
(3)
Hoya diversifolia / Muhammad Mansur / PROSEA: Plant Resources of South-East Asia
(4)
Hoya diversifolia / Wikipedia
(5)
Mangrove was plant / WILD Fact Sheets
(6)
Antibacterial Activity of Hoya Diversifolia Ethanolic Leaves Extract / Nurhidayah Ab-Rahim, Wan Ismahanisa Ismail, Muhammad Nabil Fikri Roslan et al / Biomedical and Pharmacology Journal, 2019; 12(2): pp 857-862 / DOI: 10.13005/bpj/1710 / ISSN: 0974-6242
(7)
Triterpenes and sterols from Hoya diversifolia Blume / Nelson M Panajon, Fernando B Aurique, Chien-Chang Shen, Consolacion Y Ragasa / Journal of Applied Pharmaceutical Science, 2016; 6(6): pp 79-82 / ISSN: 2231-3354 / DOI: 10.7324/JAPS.2016.60614
(8)
An Enumeration of Hoyas in Quezon Province, Luzon Island, Philippines / Elaine Loreen C Villanueva, Inocencio E Buot Jr / The Thailand Natural History Museum Journal, 2017; 11(1): pp 23-33
(9)
Hoya / Wikipedia

DOI: It is not uncommon for links on studies/sources to change. Copying and pasting the information on the search window or using the DOI (if available) will often redirect to the new link page. (Citing and Using a (DOI) Digital Object Identifier)