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Syllabication - pu-bi - calyx its pubicalyx, not publicalyx)
Hoya pubicalyx is endemic to the Philippines. It is named after its distinctive characteristics of having pubescent (hairy) calyx. Pubi is latin word for pubescent or hairy. Calyx refers to the sepals of a flower, typically forming a whorl that encloses the petals and forms a protective layer around a flower in bud.
Hoya pubicalyx was collected in Mauban, Quezon Province, Luzon Philippines on 24 Jan. 1913 on trees along streams in damp forests. It belongs to the Section Hoya.
For more detailed and technical description of this Hoya (which some of you might not want to read because yes... its too technical) just look for the "Morphology" below.
Varieties/cultivars include Pink Silver, Red Buttons, Royal Hawaiian Purple, Fresno Beauty, Reva, Bright One, Dapple Gray, Jungle Garden and Silver Sheen.
Hoya pubicalyx ‘Pink-Silver’
The green leaves with silvery splashes. These leaves turn pinkish silver in sunlight, giving the name Pink-Silver to this cultivar.
The flowers are light red in color with pink centers.
Hoya pubicalyx ‘Black Dragon’
This name is in reference to the characteristic reddish-black flowers with red centers. Bouquets of tiny black star-shaped flowers in the springtime give an exotic appearance to this Hoya.
The leaves are lime-green without any markings.
Hoya pubicalyx ‘Red Buttons’
The flowers are dark purple corollas and red coronas
The plant has purple or reddish splashes on green leaves.
Hoya pubicalyx ‘Royal Hawaiian Purple’
The Hoya Royal Hawaiian Purple has green leaves with mild flecking patterns of silvery-grey color.
The plant gets clusters of tiny pinkish-red to black star-shaped flowers. Sometimes, you can even see mixed flowers on a single bunch of the Hoya pubicalyx ‘Royal Hawaiian Purple’ plant.
Hoya pubicalyx 'Royal Hawaiian Purple' is also called Hoya pubicalyx Chimera. As a chimera (a special type of variegation) the plant is full of surprises. The lush glossy foliage, silvered as with the species can exhibit irregular sections of purplish colored leaf tissue especially visible on the young growth and newly formed leaves. The new stems are most often purplish brown as is the leaf petiole and often the leaf midrib. Flowers of mixed colors are not unusual, color mixing within one flower as well as within flowers in the globular clusters. Each cluster may appear different with occasional clusters of very dark almost black flowers, others with lighter bright rose or deep pink. It is fun to look for branches exhibiting special coloring patterns and select them for cuttings to start new and improved plants.
Pubicalyx cultivars according to Christine Burton:
‘Bright One’ (Bright blue-red corolla with rose coloured corona - differs from cv. Pink Silver in colour of corona). ‘Dapple Gray’ (I place this here though I’m not certain it belongs. Ms. Andrews who distributed it, labeled a pink flowered carnosa with this name in the picture book she rented me but all the flowers I’ve seen so labeled have been purple. ‘Fresno Beauty’ (Kloppenburg named this for his home town). ‘Grey Lady’ (I’m unfamiliar with this cultivar - I suspect it’s from England - the way gray is spelled is what gave me that notion). ‘Jungle Garden’ (From a California grower. Little different from cv. Pink Silver). ‘Jungle Green’ (No such as far as I know - I suspect that someone just couldn’t think of Jungle Garden and started calling it Jungle Green - lot of that going around)! ‘Leenie’ (named by Dr. James Broton for his wife, Eileen). ‘Pink Silver’ (the best of the best - a Hummel creation). ‘Pretty One’ (????. I question this because I once rented Ms. Loyce Andrews Hoya Photo Album. She showed this as a pink flowered Hoya carnosa look alike. The one she sold me had pink flowers too, however, everyone else I ever heard of who got a ‘Pretty One’ from her got a plant with ‘Pink Silver’ look-alike flowers with broadly ovate leaves. ‘Red Buttons’ ‘Red Buttons Seedling’ (unnamed Miyashiro seedling). ‘Reva’ (Kloppenburg named this for his mother). ‘Royal Hawaiian Purple’ (often sold mislabeled as Hoya pubicalyx var. chimera and as cv. Chimera). ‘Silver Leaf’ (similar to ‘Pink Silver’ but with rounded leaf bases and not as much silver speckling). ‘Silver Knight’ turned out to be cv. Pink Silver ‘Silver Prince’ (This turned up on the same wholesaler’s list the year after Silver Knight - turned out to be the same plant wholesaler even admitted to the truth).
Now for some photos : These are what I have in my garden
Hoya pubicalyx var. Royal Hawaiian Purple. I put the Hoya traded as Hoya fusca here because I believe it is a clone of Hoya pubicalyx var Royal Hawaiian Purple
Hoya pubicalyx "Pink Silver"
Hoya pubicalyx "Red Buttons"
My very splashy Hoya pubicalyx - possibly Hoya pubicalyx "Fresno Beauty" ?
This is another one of my very interesting Hoya pubicalyx. The leaves are all different each time. I labelled this as Hoya pubicalyx chimera or Hoya pubicalyx Royal Hawaiian Purple
Hoya pubicalyx Care
All the varieties and cultivars of Hoya pubicalyx have the same requirements including the popular Hoya Royal Hawaiian Purple plant.
The water requirement of the plant is medium. Thrice a week in summer and once a week in winter is an estimated watering frequency. Keep an eye on the soil and water when the upper 2 inches get dry. Light availability and temperature also affect the water requirement. The water requirement will increase with the increase in temperature and light exposure.
The quantity of water at one time also depends upon the soil/ substrate in use. If the plant is in heavy soil like a peaty mixture, it is better to water mildly. In the lighter substrate, you can water freely until the drainage holes start flowing out. These plants don’t like wet feet. Thus, avoid over-watering or soggy soil in order to save the plant from plant issues like root-rot.
The optimal sunlight condition is bright indirect sunlight. These plants are found growing under the trees and gaps of the forests. Thus, dappled sunlight exposure is best. In case the plant is under direct exposure, gardeners recommend covering them with 70 to 80% shade cloth. Avoid keeping them in the peak hours of direct sunlight. As this may burn the plant. However, the plant will love a little exposure to early sun resulting in brightly colored foliage.
The optimum temperature range for Hoyas is 17 to 31°C. The plant usually does well in the temperature range of 17 to 31 °C. Hoyas are not frost tolerant thus, try shifting them to warm places, when the temperature drops or when it gets really cold.
Most hoyas are generally humidity lovers. About 70% of moisture in the air is ideal for them. On drier days, consider keeping them around a humidifier.
A light, airy and well-drained soil or substrate is ideal for most Hoya pubicalyx . A good Hoya mixture may contain peat, orchid mix, and perlite in equal quantities. Cacti and succulent mix, pumice and perlite in equal quantities is also a good mixture but this is a bit heavier than the first mix so watering in this kind of mix should be lesser compared to the lighter mix.
Most Hoyas are heavy feeders. I fertilize my Hoyas every two weeks. Any fertilizer used for Orchids are ideal for Hoyas. Once a month, I give my Hoyas "supplement" like an organic seaweed fertilizer.
Hoyas need to dry out quickly. I prefer using plastic pots for my hoyas.
Hoyas like to be root bound instead of ‘floating freely’ in the pot’. Thus, it is better to avoid bigger pots/containers.
A scandent shrub, entirely glabrous except the inflorescence, the branches subterete, rather pale when dry, about 3 mm in diameter, the internodes up to 20 cm in Length Leaves opposite, fleshy, when dry coriaceous, pale and shining on both surfaces and more or less wrinkled, oblong to oblong-obovate, 10 to 14 cm long, 3 to 6 cm wide, base obtuse, apex distinctly acuminate; lateral nerves pinnately arranged, indistinct, about 6 on each side of the midrib, ascending, scarcely more evident than are the lax, indistinct reticulations; petioles about 1 cm long. Umbels many-flowered, 8 to 9 cm in diameter, the thickened rachis about 4 mm in diameter above, the pedicels spreading, slender, about 8.6 cm long, sparingly appressed-Pubescent. Flowers fragrant about 1.8 cm in diameter, brown when dry. Calyx-segments oblong-ovate to ovate-lanceolate, acute or subacute, externally somewhat pubescent, about 4 mm long. Corolla-lobes broadly triangular, about 6 mm long and wide, spreading, rotate, externally glabrous, internally densely papillose, the acuminate apex somewhat recurved. Corona 10 to 12 mm in diameter, stellate, the lobes spreading, coriaceous, brown, shining, oblong-ovate to ovate-lanceolate, acuminate, about 5 mm long, the external tip slightly refuse, the internal one ascending, the upper surface plano-convex and somewhat keeled in the median portion.