Origin and Habitat: Thailand, China, Cambodia, Laos, South Vietnam. North-Western Thailand, Indonesia (Java)
Habitat: Hoya kerriiSN|26309]]SN|26309]] grows in a small amount of medium among trees. It climbs its way up a tree trunk and curl around branches to reach for light that it requires for photosynthesis. As it grows, it forms roots that help it cling onto surfaces for support and for absorption of moisture and nutrients. It is also found in rugged limestone areas with some residual scrub vegetation.

• Hoya kerrii Craib
• Hoya obovata var. kerrii (Craib) Costantin

Description: Hoya kerrii is a robust climbing plant with curious, thick succulent, leathery leaves in form of an inverted heart and peculiar mall globe-shaped flowers, cream-white with rose-purple corona-lobes, in summer. It is a fast grower and can be trained into topiary. Hoya kerriiSN|26400]]SN|26309]] is named Sweetheart Plant or Sweetheart Hoya because of the heart or valentine shaped leaves. Hoya kerrii also comes in forms with variegated leaves. It is closely allied to Hoya obovataSN|26309]]SN|26400]].
Stems: Glabrous, pale, twinning, up to 3(-4) m long, about 7 mm in diameter. The stems produce aerial roots which in their native habitat grow into deposits of humus found in crevices and branches of trees as well as absorbing moisture from the air.
Leaves: Opposite with a thick petiole 0,5 - 2 cm long, lamina obcordate, thickly fleshy to leathery 4-12 cm long, 5-9,5 cm broad, dark green, paler and often downy beneath, broadly obovate to circular, tip deeply, 2-lobed to 10-18 mm, base rounded or broadly cuneate, margin More or less hairy and revolute.
Inflorescences (umbels): Up to 20(-25) flowered convex to globe-shaped hanging and facing the ground, 4-5 cm across; attached to a spur (single stem) called the peduncle 2-6 cm long. 3 mm in diameter, glabrous. Pedicels13-18 mm, thin, pubescent. Sepals ovate-elongate, 2,5 mm long, obtuse, outside pubescent.
Flowers: The flower shape is typical of hoya plants, small, flat, star-shaped. Each small flower is made up of two stars, one on top of the other. The so called bottom star (corolla) is larger in size than the upper centered star which is termed the corona. Corolla 9- 13 mm in diameter, creamy-white, inside papillose to densely pubescent. Corolla-lobes ovate-triangular, 4-5 x 5 mm acute, basally connate, strongly revolute: Corona pink to rose-purple; Corona-lobes broadly ovate, 2.5 mm, upper face depressed in the middle, outer append-age broadly rounded inner appendage acute. Pollinia 1 mm. The flowers are very beautiful, waxy, last almost two weeks and have a vague smell that can be closest described as chlorine. They also secrete sticky small balls of nectar, coloured red to brown, the sweet-tasting nectar is is apparently safe to eat.
Blooming: Summer.

Bibliography: Major refrerences and further lectures
1) Focke Albers, Ulrich Meve "Illustrated Handbook of Succulent Plants: Asclepiadaceae" Volume 4 Springer, 2002
2) James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11/ago/2011
3) Dale Kloppenburg, Ann Wayman “The Hoya Handbook: A Guide for the Grower and Collection” Orca Publishing Company, 1992
4) Tem Smitinand “Wild Flowers of Thailand” Printed at Aksornbandit Press, 1975
5) Hoya kerrii in: Hoyan 2(1): 12 1980
6) William Grant Craib “Contributions to the Flora of Siam.” in: Bulletin of Miscellaneous Information, Royal Botanic Gardens, Kew, London 1911(10): 385-474
7) Anders Wennström und Katarina Stenman “The Genus Hoya - Species and Cultivation”, Botanova, Umeå 2008
8) Julien Noël Costantin “Asclepiadacées.” In: Lecomte, Henri: “Flore générale de l'Indochine.” volume 4, Masson & Cie, Paris 1912

Cultivation and Propagation: Hoya kerrii isn't difficult to grow and flower. There are a few Hoya's which make ideal houseplants, Hoya kerrii or the Sweetheart Plant is one of them.
Growth rate: This is a Hoya that needs a lot of space, but it grows relatively slowly so this is normally not a problem. The all green variety tends to grow more quickly (although it's still slow by most houseplant standards) and is arguably more hardy, but it also comes in a pretty slow growing variegated variety.
Potting medium: Because it is an epiphyte, the sweet heart hoya benefits from being potted
up in a very well-draining and porous growing medium. Often specialized hoya growers either use only chopped coconut husk or a good orchid potting mixture for growing their hoya plants. The medium needs to be moisture-retentive.
Watering: Water regularly during the growing season,
Watering: With its succulent qualities it's quite adapt at storing water for longish periods of time between waterings. Water regularly in summer, but do not overwater ( wet-sensitively) and let the plants to dry out between watering and then water again. Its roots are easily lost in pots that stay damp for any length of time. Keep quite dry with ample airflow in winter (It would probably tolerate one watering a month). In the rest period no high atmospheric humidity. Care must be taken with watering as they tends to become swollen and untidy in growth habit if given too much water and shade.
Fertilization: During the growing season enrich the soil using a fertilizer rich in potassium and phosphorous, but poor in nitrogen, because this chemical element doesn’t help the development of succulent plants, making them too soft and full of water.
Exposition: Outside half shade to shade (filtered sunlight or afternoon shade tolerated) , inside it will need a reasonably light room in order to actually grow, although it will still get by even in a shadier spot and can be positioned almost anywhere in homes or offices. It subject to sunburn if exposed to direct sun for too long. Tends to bronze in strong light, which encourages flowering and heavy leaves production.
Spring: When winter ends and they begin to grow again, they will require much water and soaking the pots will no longer put the plants at risk for rot. In the spring they will grow well in partial shade and leaving them out in the rain may provide them with the water they need.
Summer: In the summer months they will tolerate heavy rain, but will be just as happy if the season is dry. They will tolerate hot weather outdoors as long as they are kept in strongly filtered light and this will encourage them to flower. They also enjoy some fertiliser. Moving the plants as they are developing buds may cause them to spontaneously abort the flowers all together.
Autumn: In the fall keep them outdoors until the night time temperatures drop below the 10°C.
Winter: Winter care presents no problems at 10° C with plenty of light. In winter be sure to take extra precautions to keep them dry, because damp cool conditions when the plants are resting is an invitation to fungal infections, but - according to temperatures –some occasional lit watering may be useful.
Pest and diseases: Hoya are generally fairly easy to grow, especially if kept pest-free. They are very susceptible to stem and root mealy bugs, and damage from these may well initiate fungal attack. Any time when there is a dead or dying stem in the pot it is important to remove it immediately and completely before other healthy stems can become ill too, isolate the healthy parts, dry them off, and re-root them in new compost.
Propagation: Easiest with leaf and stem cuttings. Above says propagation by leaf cuttings. Leaf cuttings will root, but will not grow any larger. You must have some stem attached to the leaf cuttings to get a growing plant. The stems produce aerial roots which roots root easily when inserted into a moist medium making it easy to propagate new plants from stem cuttings. Allow cuttings to dry a day before planting. It can also be increased from seeds sowing in spring in moist, sandy peat moss. Barely cover seeds. Seeds germinate quickly.
Repotting: In any season it's best to lay the stems out for several days before replanting them and then pot them only in dry soil and withhold any water until they begin to shrivel or start growing again. Re-pot every 2 years.