Urban Gardener No 23_B Annex

8/8/2019 Urban Gardener No 23_B Annex

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SPECIAL ANNEX - 23rd Issue, Vol. 3, No. 8-B ISSN 2094-1765 August 2010

GREAT VARIETY AND COLOR IN PHILIPPINE

WAX PLANT or HOYAEdited by Norberto R. Bautista

Hoya is a genus of 200-300 species of tropical climbing plants in the family Apocynaceae(Dogbane), native to southern Asia (India east to southern China and southward), Australia, andPolynesia. Common names for this genus are waxplant, waxvine, waxflower or simply Hoya. Thisgenus was named by botanist Robert Brown, in honor of his friend, botanist Thomas Hoy.

Here are some varieties of Hoya mindorensis, see their great variety in a single species.


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Hoyas are evergreen climbing vines or shrubs growing to 1-10 m (or more with suitable support intrees). They have simple opposite leaves 5-30 cm long that are typically succulent, and in manyspecies are flecked with irregular small silvery spots.

The flowers appear in axillary umbellate clusters at the apex of 2-3 cm peduncles, with repeatedclusters of flowers developing sequentially on each peduncle. The flowering peduncles get 2-3mm longer with each flowering, and can eventually reach 7 cm or more long; the base of thepeduncle is smooth, with growth subsequent to the first flowering of the peduncle is rough withnumerous tiny bracts. Each flower is about 1 cm diameter, with five thick, waxy, triangular petals;colors range from white to pink or yellow. They are sweetly scented and produce abundantnectar.

Cultivation and uses

Many species ofHoya are popular houseplants in temperate areas (especially H. carnosa), grownfor their attractive foliage and strongly scented flowers. Numerous cultivars have been selectedfor garden use. Hoyas grow well indoors, preferring bright but not direct sunlight, but will toleratefairly low light levels at the expense of rapid growth and blooming. Hoyas commonly sold innurseries as houseplants include cultivars of H. carnosa (Krimson Queen, Hindu Rope compacta), H. pubicalyx(often mislabeled as carnosa), and H. kerrii. Hoyas are easy to purchase

on the internet, and are commonly sold as cuttings, either rooted or unrooted.

Leaves

Hoya leaves vary in size, texture, color and venation. In size, leaves range from as small ascentimetre in length and from two to four millimetres in width (Hoya engleriana Hosseus) to aslarge as 25 cm. by 25 cm. (Hoya latifolia G. Don). Hoya coriacea Blume, has been reported haveleaves as long as two feet in length. One of the most succulent, Hoya kerriiCraib, has valentineshaped leaves, with notches at the apexes of the leaves instead of at the bases. H. kerrii has twoforms, one with glabrous leaves and one with suede textured leaves. There are hoyas with almostperfectly round leaves and others with linear leaves (Hoya linearis Wall. ex. D. Don and Hoyateretifolia Griff. ex Hook. f.). One popular species, Hoya shepherdiiShort ex Hook. has leavesthat resemble string beans hanging in bunches from their stalks. Hoya linearis Wall. ex D. Don is

covered with fine downy hair and greatly resembles masses of Spanish Moss (Tillandsiauseneoides) hanging from trees in its native habitat. Some Hoya leaves are smooth and shiny;some are covered with hairs. Some Hoya leaves appear to be veinless while others have veryconspicuous veins of a lighter or darker colour than the rest of the leaves. Some have leaves thatare mottled with speckles of silvery white (Hoya carnosa R. Br., Hoya pubicalyx). Some hoyashave leaves that are thin and translucent (Hoya coriacea Blume); some are so thick andsucculent that they look more like crassulas than hoyas (Hoya australis ssp. rupicola, oramicolaand saniae from Australia and Hoya pachyclada from Thailand).

Flowers

Hoya flowers are just as varied as the leaves, despite the fact that all are shaped like five pointedstars. They grow in umbels, usually with many flowers per umbel. Individual flowers range in size

from as small as four to five millimetres in diameter (Hoya bilobata Schltr.) to well over threeinches in diameter (Hoya imperialis Lindl. and H. macgillivrayi F. M. Bailey). The number offlowers per umbel varies from one (H. pauciflora Wight.) to 55 or even more. Hoya coriaceaBlume has been known to have as many as 70, each measuring nearly 2 centimetres in diameter.The single flowered Hoya pauciflora Wight makes up for its paucity by its flower size of nearly aninch and a half in diameter.

Hoya flowers vary in textures as well as size, some being glabrous and shiny and some beingquite hairy. They also vary in color. They come in the purest white, varying shades of pink fromalmost white to rubber-doll or bubble-gum pink, yellowish-pink, yellow, green, purple, brownish-


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red and brown. There are some that are so dark that they are often referred to as black. Untilrecently it was thought that a true red hoya was not ever likely to appear but recent discoveriesmake that seem possible. One of the two clones of Hoya mindorensis Schltr., from thePhilippines, which are currently in circulation, comes very close to being a true red. Blue still doesnot appear to be represented in the Hoya genus.

Selected Philippine species

Hoya bella - Beautiful Hoya Hoya benguetensis

Hoya bilobata Hoya buotii

Hoya burtoniae Hoya cagayanensis


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Hoya camphorifolia Hoya carnosaPorcelain Flower

Hoya cumingiana Hoya crassicaulis

Hoya darwinii Hoya densifolia


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Hoya deykeae Hoya erythrostemma

Hoya fischeriana Hoya heuschkeliana

Hoya imbricata (syn. Hoya pseudomaxima) Hoya kerrii- Valentine Hoya


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Hoya lacunose Hoya landgrantensis

Hoya lazaroi Hoya leytensis

Hoya loheri Hoya mcgregorii


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Hoya megalaster Hoya meliflua

Hoya merrillii Hoya mindorensis

Hoya multiflora - Shooting Star Hoya Hoya myrmecopa


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Hoya obscura Hoya pimenteliana

Hoya platycaulis Hoya potsii

Hoya pubicalyx Hoya quinquenervia


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Hoya rigida Hoya siariae

Hoya sigilliatis Hoya subquintuplinervis

Hoya tsangii Hoya vitellina


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Hoya wayetii

HOW TO GROW HOYA PLANTS

Hoya, or locally known as Shooting Star, is also known as Wax flower, Wax Vine or Wax Plant. Itis a climbing or trailing plant with thick, shiny, fleshy leaves and clusters of waxy star-shapedflowers. They are the most colorful group of plants under the Asclepiadaceae plant family, inwhich other plants like the common milkweed, the succulent Stapeliad and the Dischidia vinealso belong. They have pollen in gelatinous masses called pollinia, similar to orchids.

Robert Brown, famous for his discovery of the 'Brownian Movement' in Physics, named the plant

in honor of his friend and fellow botanist Thomas Hoy, who worked as head gardener for theDuke of Northumberland at Scion House, England.

It are about 200 to 300 species of Hoya that are native to Eastern Asia, Polynesia and Australia.It is popularly grown as a garden plant or house plant, due to its attractive foliage and highlyscented flowers. Hoyas are found throughout the Philippines at all altitudes, usually growing oncoconut trunks and tree branches. As of present, there are about 51 identified species of Hoya inthe country.


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Cultural Requirements for Hoya Plants:

Light - Hoya plants grows in diffused bright light (about 50% light). Protect it from direct sun. Forindoor cultivation, three to four hours of bright light a day are essential for healthy growth andflowering.

Watering & Humidity - Water plants regularly and do not allow them to dry out completely. Theycan benefit from moist media and occasional flooding to was away excess salts. Use soft waterlike rain water, or water low in salts. Provide a humid environment by grouping Hoya plants alongwith other shade-loving plants and watering them regularly. Allow ventilation and air-movementbetween plants at all times to prevent rotting of leaves.

Temperature. Hoya plants grows well in normal room temperature or in the lowland temperature.

Potting Technique Plant Hoya plants in plastic or clay pots with any porous and low-fertilitymixes like mixture of coconut husk cubes or coconut dust, charcoal, sphagnum moss, tree fernfiber and paslak (chopped roots of Birds nest fern). The media should be well drained and openenough so that air reaches the roots. Repot if the media breaks down, or when the plants needs abigger pot. They are usually potted as a hanging plant. For non-hanging pots, place wooden,wire or plastic coated stakes as vines tend to crawl up supports. Roll long vines around thestakes.

Fertilization. Hoya plants are light feeders. Spray a dilute solution of balanced fertilizer high inpotassium, in order to continuously produce flowers. Apply about or less of control releasefertilizers in the sides of pots.

Pruning. Prune back very long vines to induce branching. However, long vines are usually notcut, but rather trained and rolled together around stakes or wire hangers attached to the pot, asthe long vines are the ones which produces flowers.

Pest & Diseases. Hoyas are usually susceptible to sucking insects like mites, aphids and whiteflies. If insect infestation occurs, spray with a dilute solution of insecticide like Malathion, Sevin orLannate. To prevent leaf spots or rot, allow ventilation among plants, allow proper spacing and

keep plants dry between watering. Spray a weak solution of Captan or Dithane fungicide duringthe rainy season as a prophylactic to prevent fungal diseases.

Propagation. Hoyas are usually propagated by stem cuttings with 2 to 3 nodes. Leaves from thelower nodes are usually removed before the stem cuttings are inserted into the potting media.Stem cuttings are relatively easy to root especially when rooting is done under mist condition orwhen the pot is wrapped in clear plastic bag. Cuttings root best in a growing media that retain alot of moisture like coconut coir dust, coconut husk, charcoal and crushed fern chips.

Hoyas can also be propagated by seeds. Some species readily produce seed capsulescontaining tufted seeds which burst when mature and are wind dispersed. Care must beobserved by covering seed capsules with a gauze or nylon stocking when nearing maturity. Oncemature, the seed capsule slips and the seeds can be removed. Seeds can be sown and

germinated in a pot with a mixture of coir dust and sand. Transplant seedlings when they havedeveloped true leaves.

Hoya are interesting plants to collect, and some garden clubs, local and abroad, are formed justto cater for the growing of this plant. Conservation is also needed for this group of plants.

All photographs from Mr. Wally Suarez & Wendy Regalado. Parts published in the Urban Gardener, ManilaBulletin and Philippine Star. Written and Edited by Norberto R. Bautista c/o The Plant Biotechnology Project,Research & Development Center, Rizal Technological University, Boni Avenue, Mandaluyong City, Philippines.

August 2010

Documents

Urban Gardener No 23_B Annex