HOYA CARNOSA: CHARACTERISTICS, VARIETIES, PROPERTIES, CULTIVATION - BIOLOGY - 2024

La Hoya carnosa is a gnarled shrub cultivated as an ornamental plant belonging to the family Apocynaceae. Known as matchstick, clepia, hoya, wax flower, nacre flower, porcelain flower or wax plant, it is a species native to Southeast Asia.

It is an evergreen shrub with a creeping or climbing habit, with long thin stems with opposite, leathery and fleshy leaves of bright green color. The star-shaped, waxy-looking flowers are grouped in umbelliferous inflorescences, which is the main attraction of this ornamental species.

Hoya fleshy. Source: pixabay.com

Its natural habitat is located in regions with a tropical and subtropical climate, as well as temperate environments with a warm and cool climate. Under conditions of partial shade they develop vigorously and their flowering is abundant, provided they receive good lighting throughout the day.

It is a highly appreciated species as an ornamental plant for its low maintenance and attractive flowers grouped in aromatic inflorescences. It is usually grown around fences or hanging baskets with stakes that allow it to hold its wide climbing branches.

General characteristics

Appearance

Broadly branched semi-woody shrub with thin, cylindrical, dark green climbing stems. It can reach 5-6 m in length. The ramifications are herbaceous or semi-woody, but the base of the stem tends to lignify with time, being woody in adult plants.

Leaves

The simple leaves 8-10 cm long by 4-5 cm wide are thick oval, succulent, petiolate and leathery. They are arranged in the opposite way and are bright dark green in the shade or slightly yellowish in full sun exposure.

flowers

The fleshy, aromatic, star-shaped flowers are 1 to 2 cm in diameter and are grouped 10-30 units in compact umbels. The corolla has 5 white triangular lobes, welded at the base with a waxy consistency and an irregular surface. In turn, the ginostegio forms a reddish or purplish starry crown in the center.

The inflorescences are located on a 4-6 cm long peduncle and are born from the leaf axils along the stems. Flowering occurs during the spring and summer seasons, remaining on the plant for a long time without wilting.

Fruit

The fruit is a dehiscent fusiform follicle 8-10 cm long and 10 mm wide, which develops occasionally. Inside there are numerous seeds of 5-10 mm in length, each one equipped with a silky crest that favors their dispersion by the wind.

Hoya carnosa leaves. Source: No machine-readable author provided. MPF assumed (based on copyright claims).

Taxonomy

- Kingdom: Plantae

- Subkingdom: Tracheobionta

- Division: Magnoliophyta

- Class: Magnoliopsida

- Order: Gentianales

- Family: Apocynaceae

- Subfamily: Asclepiadoideae

- Tribe: Marsdenieae

- Genus: Hoya

- Species: Hoya carnosa (L. f.) R. Br.

Etymology

- Hoya: generic name given in honor of the 18th century English gardener and botanist Thomas Hoy.

- fleshy: the specific adjective comes from the Latin term "carnosus" which means fleshy. Derived in turn from "caro, carnis" which means meat; plus the suffix "osus", which means abundance. Alluding to its showy and aromatic succulent flowers.

Detail of the flowers of Hoya carnosa. Source: Frank Vincentz

Varieties

At a commercial level, varieties have been developed with flowers of different colors and curved or variegated leaves. Among them the varieties stand out:

- Hoya carnosa var. formosana (T. Yamaz.) SS Ying

- Hoya carnosa var. gushanica W. Xu

- Hoya carnosa var. japonica Sieb. ex Maxim.

- H. carnosa f. compacta: known as hoya carnosa compacta, it is a rolled-leaf cultivar.

Associated species

- Hoya australis: native species of Australia. It is characterized by its white, waxy and fragrant flowers, as well as its succulent and rounded leaves 8-9 cm wide. Its natural habitat is located in tropical jungles and wooded regions, which adapts to hot climates and tolerates little cold.

- Hoya bella: plant with climbing habits, small oval leaves and sharp apex, which can measure 2-3 cm across. The flowers are grouped of corymbs of 5-12 units, hanging flowers, waxy and white with a purplish center.

- H. globulosa: native Himalayan species also known as Hoya vilosa. Oval leaves 10-15 cm long by 3-5 cm wide, light green with darker veins. Small flat, aromatic, white flowers with reddish lines on the crown.

- H. longifolia: native species of the Himalayas, adapted to cold climates. Bright green lanceolate and fleshy leaves, creamy-whitish flowers.

- Hoya linearis: native species of the Himalayas cultivated as a hanging plant. The stems are thin and the elongated leaves grow in a spiral. The inflorescences, less rounded, group small triangular white flowers with a creamy center. They are very fragrant.

- Hoya multiflora: species native to Malaysia. Lanceolate leaves with a leathery appearance and a glossy dark green color. The flowers are pale yellow with a brown center, being grouped in numerous inflorescences.

- H. purpureo-fusca: species native to Indonesia and Malaysia. Fast-growing vine, succulent green leaves and small grayish spots. Brown or purple flowers with a thin whitish band and the center of pinkish tones.

Hoya carnosa in its natural habitat. Source: Paulo RS Menezes

Properties

The wax flower does not have defined properties, its main use is as an ornamental plant. Its strong and intense aroma can be pleasant on cool days, but unpleasant when the environment is highly charged.

As an indoor ornamental, it is grown in hanging baskets. In hot environments it can be sown in flower boxes protected from direct solar radiation.

Culture

Spread

Vegetative propagation by means of cuttings or layering are the most used methods to multiply the wax flower. For propagation by cuttings, terminal herbaceous stems with 2-3 nodes are selected, trying to eliminate the leaves from the base of the cut.

It is advisable to impregnate the cutting with phytohormones and sow in rooting chambers using a homogeneous mixture of peat and perlite as a substrate. Under conditions of constant temperature and relative humidity, with frequent applications of mist irrigation, the cuttings take root after 15-25 days.

In the case of propagating the wax flower by layering, it is important to select healthy, firm and vigorous semi-woody branches. The technique consists of removing a 10-15 mm ring of lignification tissue from the bark, a space that must be impregnated with powdered rooting phytohormones.

With the use of a dark plastic bag, the cut is covered with a mixture of black peat and perlite in equal parts. Both ends are closed with a string firmly to prevent loss of substrate or penetration of insects.

From time to time it is advisable to moisten the substrate, in order to maintain constant humidity and favor the formation of adventitious roots. With this technique, new seedlings can be obtained after 25-30 days.

Umbel of Hoya carnosa. Source: Fan Wen

Sowing / transplanting time

The best time for propagation, both by cuttings and by layering, is during spring, once the frosts have finished. Similarly, transplantation of rooted cuttings and layers is done during the spring.

In the case of plants planted in pots, it is advisable to change the plants to larger pots every 2-3 years. In order to promote the growth and development of new roots, as well as maintain the vigor and floral performance of the plants.

Requirements

- The wax flower requires a well-lit location, but not in full sun exposure. It is advisable to grow in partial shade in a place where it receives the first rays of the day and the last rays at the end of the afternoon.

- It develops in cool or warm climates where temperatures stay between 16-26 ºC. It does not tolerate temperatures below 5 ºC, nor above 30 ºC.

- It grows on fertile, loose and permeable substrates, preferably enriched with compost or worm castings and pieces of charcoal. Clayey and heavy substrates that can be compacted should be avoided, since they would cause rotting of the roots.

Care

Location

The wax flower is an ornamental indoor plant, adapted to semi-shady conditions as long as it has good lighting throughout the day. It develops in warm and cool environments, it is susceptible to low temperatures and occasional frosts below 10 ºC.

Substratum

It prefers loose and well-drained substrates, the ideal substrate being a mixture of black peat, perlite or fine sand and organic matter. It is recommended to add pebbles, pieces of wood or fragments of organic carbon to avoid compaction of the substrate.

Illustration of Hoya carnosa. Source: Francisco Manuel Blanco (OSA)

Irrigation

This species requires frequent watering, especially during the summer when the substrate tends to dry out more quickly. It is recommended to water 2-3 times a week. Its fleshy leaves store water, making it drought tolerant, however the rest of the year it can be watered every 8-10 days.

During winter, if the temperature drops below 10ºC, it is advisable to stop watering until the temperature rises. In general, the leaves become stiff when the substrate is dry and the plant requires irrigation.

Subscriber

During spring and summer, monthly applications of foliar fertilizer or universal chemical fertilizer for garden plants are recommended. In early autumn it is appropriate to make an amendment of organic fertilizer at the time of applying the irrigation.

Pruning

The wax plant does not require frequent maintenance pruning, it only needs the use of guides or tutors for them to develop widely. The first flower stalks should not be cut, as new inflorescences emerge from them in the next season.

Pests

Under suitable conditions it is a rustic plant to attack by pests, although under adverse conditions it can be affected by mealybugs and aphids. Mealy bugs, lice or aphids feed on the sap they suck from the tender tissues and flower buds. Its control is carried out with physical methods and the use of chromatic traps.

References

1. Hoya carnosa (L. fil.) R. Br. (2018) Catalog of Life: 2020-01-10 Beta. Recovered at: catalogueoflife.org
2. Hoya fleshy. (2019). Wikipedia, The Free Encyclopedia. Recovered at: es.wikipedia.org
3. Sánchez, M. (2018) Wax flower. Gardening On. Recovered in: jardineriaon.com
4. Hoya (botany). (2019, October 30). Wikipedia, The Free Encyclopedia. Recovered at: es.wikipedia.org
5. Granados, K. (2019) Characteristics of the Clepia or Flor de Cera. Our Flora. Recovered at: ourflora.com
6. Puccio, P. (2013) Hoya carnosa. Monaco Nature Encyclopedia. Recovered at: monaconatureencyclopedia.com