The Hoya genus encompasses diverse epiphytic plants, cherished as houseplants for their unique foliage and fragrant, star-shaped flowers. Among many species, Hoya pubicalyx and Hoya memoria are popular, yet often confused due to similar appearances. This article clarifies distinctions between these two plants, providing insights into characteristics, history, and care for accurate identification and cultivation.
Hoya pubicalyx: Characteristics and Varieties
Hoya pubicalyx is a vigorous vining plant. Its elongated, glossy leaves range from deep green to almost black, often with silver flecks or “splash”. Young leaves can sometimes emerge burgundy before maturing to green.
The flowers are star-shaped, appear in dense clusters, and release a sweet fragrance. Colors vary across cultivars, including shades of pink, red, purple, and nearly black. Popular varieties include:
‘Splash’ with prominent silver markings.
‘Red Buttons’ with deep burgundy blooms.
‘Pink Silver’ featuring abundant silver splash and pink flowers.
‘Royal Hawaiian Purple’ producing nearly black flower clusters mixed with pink.
Hoya memoria: Characteristics and History
Hoya memoria has slender, trailing vines and floral displays. Its small, dark green, glossy leaves often have subtle silver speckles. These narrowly elliptical leaves, with pointed tips, reach about 2 inches long and 0.8 inches wide. Under bright light, foliage can develop a reddish tint.
Hoya memoria flowers are star-shaped, typically pink, red, or pinkish-orange, often with white or yellow centers. These blooms have a sweet, often caramel-like fragrance. Named to commemorate Manila’s Memorial Gardens where it was found in 1981, Hoya memoria was often misidentified as Hoya gracilis or a Hoya pubicalyx cultivar, but is now recognized as a distinct species.
Direct Comparison: Distinguishing Features
Distinguishing Hoya pubicalyx and Hoya memoria involves examining their leaf and flower characteristics. Though both are vining plants with foliage and fragrant blooms, subtle differences exist.
Hoya pubicalyx leaves are larger, broader, ovate or lance-shaped, often with silver splash. In contrast, Hoya memoria has smaller, more elongated, narrowly elliptical leaves, thinner and often with finer silver speckles. New foliage on H. pubicalyx can be burgundy; H. memoria leaves may blush pinkish-brown in strong light.
Hoya pubicalyx flowers have a wider range of colors (pink, red, purple, dark maroon) and a sweet fragrance. Its corolla is dark rose-pink with white margins and is densely hairy inside. Hoya memoria flowers are consistently pinkish-orange to red, often with a red corona and yellow center, and possess a distinct sweet caramel scent.
Growth habit also differs. Hoya pubicalyx is a vigorous climber, reaching long lengths. Hoya memoria is also vining, but does not naturally twine and may require support to climb, making it suitable for hanging displays.
Care and Cultivation
Both Hoya pubicalyx and Hoya memoria share similar care requirements, reflecting their tropical origins. They thrive in bright, indirect light; direct harsh midday sun can scorch leaves. An east-facing window or filtered sunlight is ideal.
Allow soil to dry between waterings to prevent root rot, due to sensitivity to overwatering. They prefer well-draining potting mixes with perlite, bark, or coco husk. A warm environment (60-85°F / 16-29°C) benefits both plants. Higher humidity (40-60%) encourages growth and flowering. Fertilize with a balanced, diluted water-soluble fertilizer during spring and summer, reducing feeding in winter.
Choosing and Identifying Your Hoya
Identifying your Hoya focuses on a few features. Leaf morphology is key: Hoya pubicalyx has broader, larger, and sometimes more heavily splashed leaves, while Hoya memoria has narrower, more elongated leaves and finer speckling.
Flower characteristics also provide clues. Observe the color palette: Hoya pubicalyx has a wider range of dark pinks, purples, and near-blacks; Hoya memoria is pinkish-orange to red. The distinct caramel-like scent of Hoya memoria flowers is a reliable indicator.