1

15th Issue Vol. 2 No. 12 ISSN 2094-1765 December 2009

Growing Dendrobium Orchidsby Norberto R. Bautista

Dendrobium is one of the widely cultivatedorchid in the Philippines, and is also one ofthe largest genus of tropical orchids, whichis composed of about 1200 species. Theplants also exhibit a variety of sizes andshapes, including flower color, scent andsize. Dendrobiums are found in diversehabitats throughout much of south, east andsoutheast Asia, including the Borneo,Australia, New Guinea, New Zealand andPhilippines. It is one of easiest to grow andaffordable for orchid enthusiasts. ThePhilippines has a lot of Dendrobium speciesto offer, however, most of them arebotanicals and has flowers that last only 1day (one day orchid).

The name Dendrobium came from theGreek 'dendron' (meaning tree) and bios(meaning life), as they are often foundclinging in tree branches. The species areeither epiphytic (tree growing) oroccasionally lithophytic (rock growing). Theplants have adapted to a wide variety ofhabitats, from the high altitudes in theHimalayan mountains to lowland tropical

forests and even to the dry climate of the Australian desert.

Dendrobium orchids are sympodial and have pseudobulbs, which is composed of long reedlikestem with a length of about 30 cm and used as storage organ for water and food. There are alsominiature types, about 3-5 cm tall or the tall ones, measuring a meter or two in height. Thepresence of pseudobulbs help the orchid survive in dry periods and oftentimes during occurenceof drought. Some peeudobulbs appear densely covered with short white hairs. The leaves areshort and ovate-shaped, growing alternately over the whole length of the stems. However, thereare times that the pseudobulb loose its leaves and becomes bald.

The floral blooms or flowers develop in the upper part of the stem or pseudobulb. Flower colorranges from white, yellow, pink, orange, violet, red, or blue, with various shapes, sizes, stripesand forms. Flowers on plants usually last 2 to 4 weeks.Some species are in great demand byorchid growers and collectors as they are used in breeding works to produce hybrids. Somehybrids are well sought after by florists.Dendrobium phalaenopsis is one of the most importartspecies since it is used in all Dendrobium cutflower variety breeding.

2

Inter-species breeding has resulted innumerous varieties and hybrids, whichmakes the plant a wonderful breedingmaterial.

Dendrobiums are widely bred and grown inHawaii and in Thailand. The flowers aremade into a lei neclace used to welcomeincoming tourists, and may also be used as agarnishing in food preparation. Somespecies are even medicinal, while others areused as in handicrafts, as their dried yellowstem is used to adorn baskets or belts. It isalso a very important cut-flower material bothlocal and abroad, specially the white andviolet colored ones.

How to grow this plant.

The Dendrobium have a sympodial type ofgrowth habit, wherein each new pseudobultarise from pre-existing old canes. Thepseudobulbs are capable of storing waterand nutrients thus, the growth of newpseudobulbs is dependent on the previewsold pseudobulbs.

CULTURAL REQUIREMENTS

Light. Matured Dendrobiums grow in60% sunlight up to 75% sun,provided that they are protected fromintense heat and light at noontime, toprevent scorching of leaves. Shadenets are used to provide the rightamount of light, or plants are placedin eves of houses. For seedlings,they may be grown in 50% shade, butlater needs to be adjusted in higherlight intensity for flower initiation.

Potting Techniques. Dendorbiumscould be planted either in plastic orclay pots, and the plant have to be

properly stalked or anchored in the center of the pot using GI or copper wires. The plant may alsobe mounted on live trees or dead wood, and plants needs to be anchored properly of else theywill fail to root. Dendrobiums flower within 1.5- 2 years from seedlings.

Watering. The rate of watering depends on location, wind movement, and light intensity. Wateronly when the media is dry; and allow plant to dry (not bone dry) before another watering.Spraying water all over the plant using a water hose until the plant is dripping wet is satisfactory.

(Top Left is a yellow Dendrobiumchrysanthum, while below is thefamous Dendrobium Sonia.)

3

The plants needs to be wateredregularly, and changes in wateringfrequency usually causes the plantto shed its leaves. Ventilation orwind movement is very importantin drying the plant. Plants needs tobe kept dry a few hours afterwatering. Water soaked plantstend to rot. Use an industrial orelectric fan to dry plants if windmovement is not available.

Flowering. Plants flower whenmature, and when well exposed tolight, and well fertilizedand watered. 1.5 to 2.0 old plantsusually mature enough to flower.After flowering, they need a restperiod of about 6 months to floweragain.

Fertilization. Dendrobiums needto be fertilized using a dilute orchidfoliar fertilizer solution once everyweek. Follow the recommendeddilution rate in the label offertilizers. Fertilize the plants earlyin the morning, as nutrients arecommonly absorbed by the leavesand roots in the presence of light.

Dendrobium White Pagoda

Potting Media. Dendrobiums are epiphytes and usually grow on tree trunks in theirnative habitat. In culture, they could grow on coconut husk, charcoal, croaks (broken pottery), andchopped tree fern, acacia wood, or caimito branches. For coconut husks, they need to be soakedfirst overnight for 2 days for the tanins to be leached out before using. These tanins prevent theplant from rooting properly.

Pests and Disease Management. Dendrobiums are often attacked by weevils, whichbore holes on the canes or pseudobulb, and they are very difficult to eliminate. Weevils can beeliminated by handpicking or spraying of a systemic insecticide. Sucking insects like thrips, mitesand scales also attack Dendrobiums, and they can be controlled by a dilute spray of Lannate orSevin insecticides. During rainy season, spray fungicides like Dithane or Captan to protect plantsfrom rotting.

Propagation. Conventionally, Dendrobiums could be propagated through division ofpseudobulbs. Plants can be divided using sterile pruning shears into 3 pseudobulbs each andmounted on clay pots with charcoal or coconut husks. The wound needs to be sealed with afungicides paste (a teaspoon of water added in 2 teaspoon fungicide powder) to prevent entry offungal diseases into the wound. The fastest and efficient way of propagation is through seedculture technology in the laboratory. Flowers of selected plants are pollinated, and their seedcapsule are allowed to mature. Dendrobium seed capsules mature in about 3 months. Theyusually contain about 20,000 seeds! The seeds are then sown in the laboratory in a glass vesselwith an artificial nutrient medium, when the seeds will germinate till they become hardy seedlingsin a years time. Then, they are out-planted in the nursery where they mature from 1.5 to 2 yearstime.

4

Weirdest of the Weird

The Philippine Rafflesiaby Norberto R. Bautista & Photos by Julie Barcelona

A Rafflesia schandenbergiana comparable to that of a child. It is the 2nd largest rafflesia recorded

Rafflesias are enigmatic group of parasitic flowering plants which deserves attention as it isunique, intriguing, and at the same time endangered. Their survival will depend on how we takecare of our forest. It is a plant not intended for the home garden, however, it will be a verypopular plant to attract foreign tourists in a botanical garden. The plant has no stems, leaves or true roots. Strange, right? It is an endoparasite of a specificplant host, the Tetrastigma vine which belongs to the Vitaceae or grape family. The Tetrastigmavine is its only host, thus, theoretically, if you want to grow Rafflesia, you have to grow theTetrastigma vine first through stem cuttings, and introduce the seeds later. The Rafflesia spreadsits root-like haustoria inside the tissues of the vine, and absorbs its host’s sap until it matures.The only part of the plant that can be seen outside the host vine is the five-petaled flower, rangein size from 3 feet wide to 6 inches in diameter. An Indonesian guide working for Dr. Joseph Arnold in 1818 discovered the first Rafflesia plant inthe rain forest of Indonesia. The plant was named after Sir Thomas Stamford Raffles, the leaderof the expedition.

5

A Rafflesia baletei (left) and a Rafflesia banahawensis

The genus contains approximately 27 species all found in southeastern Asia, on the MalayPeninsula, Borneo, Sumatra, and the Philippines. The Philippines has 9 species namely: R.schandenbergiana (2nd largest in the world, and the largest in the Philippines), R. speciosa, R.panchoana, R. mira, R. manillana (the smallest), R. lobata, R. leonardi, R. banahawensis and R.baletei. Our country is the center of Rafflesia research. The plant group belongs to the mysterious Rafflesiaceae family. With the advent of DNA tests, itwas revealed that comparing the mitochondrial DNA (mtDNA) sequences of Rafflesia with otherangiosperm (flowering plants), it was indicated that this parasite evolved from photosyntheticplants of the order Malpighiales and is closely related to the family Euphorbiaceae (where yourPoinsettia and Euphobia plants belong), which is astonishing as members of that family typicallyhave very small flowers.

The Rafflesia plants areconsidered the "Queens of theParasites," as one species,Rafflesia arnoldii (the largest ofits kind and is found inIndonesia), has enormous three-foot wide, waxy-looking red andwhite-freckled blossoms whichsmell like rotting corpse. Theflowers’ smell gave the plant itslocal names which translate to"corpse flower" or "meat flower".

Dr. Barcelona inspecting a R. manillana in its natural habitat…

Yet not all Rafflesia blooms are monster-sized. Some produce only smaller, palm-sizedblossoms. The smallest, R. manillana, has 20 cm diameter flowers.

6

R. speciosa (left) and R. panchoana (right)

The vile smell that the flower gives off attracts insects such as carrion flies or blue bottle flies,which transport pollen from male to female flowers. Little is known about the plant’s seeddispersal. However, tree shrews, rodents and other forest mammals apparently eat the fruits anddisperse the seeds. Rafflesia is an official state flower of Sabah in Malaysia, as well as for theSurat Thani Province, Thailand. The Rafflesia flower is the icon of plant conservation works inSoutheast Asia. The Rafflesia shares its characteristic corpse-smelling flowers to the Pungapung Arum plant

(Amorphophallus titanum) of the Araceaefamily. Both Rafflesia and Amorphophallus areflowering plants, but they are distantly related. Even though it has a very attractive lookingflower, there has been no technology yet tocultivate the plant in gardens or ingreenhouses. It relies primarily to its host, theTetrastigma vine, in order for the plant to live. Thus, research has been being done in orderto grow the Tetrastigma vine and then toinoculate the Rafflesia plant into it.

Rafflesia lobota Most folks never get to see this plant in bloom as the Rafflesia rarely blossom, sometimes takingfive to 10 years between flowerings. And they're found only in remote Malaysian, Indonesian andPhilippine rain forests. The life cycle of this plant is still an enigma. People tend to see the plant only when it flowers,and it is found only in a specific location. Thus, there is a need to protect sites where the plant isfound, or else, the plant disappears when its forest site is destroyed and converted intoagricultural land.

7

Rafflesia blooms usually in the rainy season, and begin to senesce in a few days, turning to slimy,black masses. A phenomenon in the plant kingdom, Rafflesia may be the "giant panda of theplant world." Though a single female flower may produce thousands of seeds, and likelydispersed by tree shrews, rats and other wildlife, but their survival is still in question. Seedsrarely find host vines, thus, elevating their unpredictable flowerings. Malaysian and Indonesian botanical gardens usually use Rafflesia species to tourists, andprotect specific sites where the plants grow. We hope to see a horticultural technology bedevelop to cultivate and propagate Rafflesia in botanical gardens or greenhouses in thePhilippines. Philippine species Filipino scientists and botanists has been tremendously active since 2002 in discovering andnaming several new species of Rafflesia. Before this time there were only two species known: R.manillana and R. schadenbergiana, the latter of which was last seen in 1882 on Mt. Apo in DavaoProvince, Mindanao and was thought to be extinct. However, in 2002 Dr. Julie Barcelona and Dr. Edwino Fernando discovered Rafflesia speciosa inthe mountains of Antique Province. Three years after, in 2005, another Rafflesia was Dr.Fernando and Dr. Perry Ong on the remote Mt. Candalaga, Maragusan, Campostela ValleyProvince on Mindanao. It was named Rafflesia mira. Another group (that of Dr. Domingo Madulid and his co-workers published another name (R.magnifica) later, however, R. mira stands as the nomenclaturally valid name. R. mira (45-60 cm indiameter), is approximately the same size as R. speciosa (45-56 cm) of Antique Province, butdefinitely larger than Luzon’s R. manillana (14-20 cm in diameter). In April 2005, during his expedition to Mt. Igtuog and Mt. Sakpaw in the Central Panay mountainrange, Renee Galang discovered a previously undescribed Rafflesia which was later named R.lobata by Galang and Madulid in 2006. In 2006, a previously collected and undescribed species by Danny Balete in 1991 from the BicolRegion was recognized. Dr. Barcelona, Mary Ann Cajano and Dr. Annalee Hadsall named it R.baletei in honor of its discoverer after field work has confirmed it to be different from R.manillana. Several new populations have also been seen in the Camarines Sur Province,specifically in Mt. Isarog and Mt. Asog (or Mt. Iriga). Moreover, in 2007, Dr. Julie Barcelona reports on the discovery of yet another population of therare R. schandenbergiana in Bukidnon. In the same year, a new Rafflesia species was discovered in Mt. Banahaw in Luzon, a populardestination for mountaineering and religious groups. It is an unlikely spot to find a new species of

8

this strange plant. But such was the case and two papers was published naming it R.banahawensis by Dr. Madulid and another by the group of Dr. Barcelona Dr. Madulid and co-workers also discovered on the same year (but published in 2008), throughadditional field and herbarium work on the Rafflesia known originally as R. manillana from Mt.Makiling yielded the description of a new species, R. panchoana. In 2008, in the remote sitio Kinapawan in the coastal town of Lallo in Cagayan Valley, a newRafflesia was made known to Filipino botanists. Working with CAVAPPED, ConservationInternational (CI), and DENR staff, Dr. Barcelona traveled to the site and collected the type of thisRafflesia. She named it R. leonardi, in honor of Leonardo Co, who is an expert on the CagayanFlora. It is similar to R. manillana of Samar and Luzon and R. lobata of Panay by the widediaphragm aperture and flowers that grow on the roots and aerial portion of the vine. It is,however, different in its larger size (to 34 cm), central disk that is nearly smooth or with markedlyreduced processes, and the absence of white blotches/windows inside the floral tube. It is the 5thRafflesia found on Luzon and the 9th from the Philippines. An advocacy in protecting and conserving our last remaining forest is being spearheaded by thePhilippine Native Plant Conservation Society.

The Santan (Ixora) With a New Twist.By Lawrence Chan

The Santan is a popular cultivated ornamental shrub, flowering year-round, and requiring littlecare. It grows from half meter to 4 meters height in height, and the plant is highly trainable as ahedge, and sometimes as a bonsai. There are now hundreds of colorful hybrids that arecommonly cultivated in towns and cities. There is the usual sized Santan, and there is also thedwarf varieties.

Flower cluster comes in color of white, yellow, red, red orange, tangerine, pink, and they arewithout fragrance. But for some species like Ixora finlaysoniana or Santang Puti , the flower ishighly fragrant.

The lowly Santan, or Ixora sp isone of the oldest known floweringplant and is internationally knownas Jungle Geranium, Flame ofthe Woods, and Jungle Flame.Its name was derived from anIndian deity. The genus Ixora iswidespread in Indian sub-continent, China, Indo-China,Malayan peninsula to Indonesia,and the Philippines, withapproximately 420 to 450species. The plant isrepresented with approximately45 species in the Philippines.

9

Folkloric Uses

The Santan has some folkloric uses. In most parts of the Philippines and other Asian countriesthe flowers are used in making colorful leis and commonly planted as hedges and in containerpots. Plant parts of Ixora like leaves, stems, roots and flowers are utilized in traditional medicines.The flower decoction is used for the treatment of hypertension, amenorrhea and irregularmenstruation. The decoctions of leaves are also used for wounds and skin ulcers, while thepoulticed fresh leaves and stems are used for sprains, eczema, boils and contusions. The dilutedtincture of roots is used for mouthwash and gargles for sore throat.

Cultural Requirements of the Plant.

Light. The santan is grown in full sun, which induces its year round flowering. It is used inlandscaping in open areas, usually exposed to bright light. Plants placed in shaded areas doesnot bloom much.

Watering and Fertilization. In order to maintain a healthy plant, regular monthly fertilization ofcomplete fertilizer 14-14-14 recommended. Apply about one-half teaspoon of complete fertilizerper plant every month in order to induce healthy growth and produce more flowers. For verysunny areas, water the plant once a day or once every 2 days. Santan plants are very hardy andcan tolerate slight drying.

Potting Techniques. The plant grows in practically any type of soil, but it will thrives best in richsandy loam. For best results, mix a potting medium composed of equal parts of sand, garden soiland compost. The plants needs to be watered regularly in order to stay active and healthy.Small plants can be established in 8-inch clay pots, but often times, these plants are planteddirectly into the soil.

Controlling Pest & Diseases. Plants are easily attacked by several kinds of insects like ants,mealy bugs and aphids. To control insect infestation, spray plants with insecticides like Malathionor Lannate. Spraying a systematic insecticide would eradicate these sucking insects. Regularpruning is also necessary, in order to remove dead branches and also to induce it a bushyappearance.

The Santan is the ideal plant for low-maintenance landscaping, usually planted in roadsides andpublic places due to its capability to thrive in neglect, it is very affordable, and produces an all-year round bloom. Plant propagators in Tabang, Bulacan and Bay, Los Baños, Laguna producedifferent varieties of Santan by the thousands for landscapers in the city.

Propagation. Santan is commonlypropagated through stem cuttings ,marcotting and layering. For hedgesand mass plantings, pruning is doneright after blossoms have withered tomaintain height of 30-60 cm. Forbreeding purposes, the Santan flowercan be pollinated for it to producefruits or berries which contain theseeds.

There is a trend now of producingnewer varieties of santan, usually thebright orange once.

10

The Colorful Moon Cactiby Norberto Bautista

If you will be visiting some plant shops like those at Manila Seedling Bank at QuezonAvenue corner EDSA in Quezon City , you would see some very colorful round cactigrowing on top of another green-stemmed cacti. For plant amateurs, this would look likeflowers coming out of a cacti, but actually these are 2 cacti grafted together.

Almost any two cacti can actually be successfully grafted, and produce some interestingforms. Cacti grafting is usually done in order to: (1) Save plants severely rotted ordiseased, by grafting the remaining healthy portion of the plant onto another cactus; (2)to ensure better growth and flowering by grafting scions of slow growing species ontovigorous, fast-growing stocks; and (3) to develop unusual growth forms.

Grafted cacti are novelties which are being sold in some plant shops in Quezon City .The most common of these novelty cacti is the “Moon Cacti”, a marketing name, andwhich mostly mass-produced from Korea . With brightly colored scions of red, orange,yellow, or white atop green stocks, the “Moon Cacti” are quite striking. The sources ofthe colored scions are mutant seedlings lacking the green chlorophyll pigment. Thesewild mutant color variations are artificially induced probably by irradiation Theseseedlings would not live by themselves for more than a few weeks since the absence ofchlorophyll prevents them from making food by photosynthesis. As tiny seedlings theyare grafted onto vigorous green stocks, which provide the materials to support thecolored scions. The top cacti used as a scion is Gymnocalycium mihanovichii friedrichii(also commonly known as 'Hibotan'), a desert cactus, while the grafted green stem orroot stock is Hylocereus trigonus, a jungle cactus.

These “Moon Cacti” can grow for years, but when the green tissues of the stock begin tocork over from old age, re-grafting to a new stock is necessary or the scion will slowlystarve to death.

Grow the plant as you would to other cactus. Place you Moon Cactus in a locationwhere it will get bright indirect light, or even in a window that gets a few hours of directsun - preferably morning or late afternoon sun. Avoid placing them in an area where itwill receive hot direct mid-day sun, or else the plants will be scorched. Water the plantthoroughly, and don't water again until the pot is fairly dry about down to a depth of 1" inthe soil. You may water them every other day or every 3 days. Do not over-water yourplant, for this this will cause rotting of the root system, and kill your plant. It will benefitfrom a monthly drenching of dilute fertilizer solution composed of about ½ teaspoon ofcomplete balanced orchid fertilizer dissolved in 1 galloon water.

11

The Urban Gardener is an official electronic publication (in PDF Format) of the Plant BiotechnologyProject, Research & Development Center, Rizal Technological University, Boni Avenue, MandaluyongCity, Philippines. It is published monthly. For more information, please inquire thru email:rdc_rtu@yahoo.com or plantbiotech_rtu@yahoo.com and landline (+632) 534-8267 Local 135 or Fax(+632) 534-9710.

All articles in this month’s issue was written and edited by N.R. Bautista © November 2009

The Plant Biotechnology Project Committee is composed of: Alexander B. Quilang, Norberto R. Bautista,Jovita A. Anit & Carnette C. Pulma.

A batch of colorful moon cacti – non-photosynthetic cacti grafted on another cacti species forsurvival. They are nice decorations during Christmas due to their red and yellow color.

These plants may sometimes suffer from sucking insects like mites, thrips, scales andaphids. If insect infestation occurs, spray them with an insecticidal solution of eitherLannate or Sevin with a little drop of dish-washing detergent as a sticker once everyweek for 3 weeks.

Use a sandy loam soil mix that drains well and allows some drying out betweenwaterings. Top dress with small pebbles or coarse gravel for quicker water drainage.Place them either in plastic or clay pots