Updated: May 10, 2021
In the Hoya world, Hoya lacunosa is considered one of the favorites due to its fragrance and its distinctive foliage. It is named after its prominent characteristics of having “lacunose leaves/surfaces (cupped or sunken between the veins). Hoya lacunosa is from the latin word “lacunosa” or lacunose in English.
lacunose Having or full of lacunæ; furrowed or pitted; marked by gaps, cavities, or depressions; specifically, in botany and entomology, having scattered, irregular, broadish, but shallow excavations, as a surface. A lacunose leaf has the venation salient beneath, leaving the surface full of hollows.
Hoya lacunosa belongs to Hoya section Otostemma, which includes the similar species Hoya obscura,Hoya sipitangensis,Hoya walliniana, Hoya nabawanensis, Hoya pusilla and Hoya endauensis.
The species placed in section Otostemma are markedly similar, all having fairly small ovate to lanceolate leaves set closely along the stems and a partially pendant growth habit. The flowers of these species are also quite similar, being comprised of persistent umbels of small, usually revolute* cream colored flowers with pale yellow to red-rimmed coronas. Some species or forms have a pinkish blush to the corollas, as does Hoya obscura and Hoya lacunosa 'Tove'. The plants in this section also have similar fragrances; light, spicy, and reminiscent of carnations and some with fragrance similar to Jasmine flowers.
Hoya lacunosa is a variable species which occurs over a wide range. Early collections seem to have come from Java, but early written descriptions cited the range of H. lacunosa as being the entire "Indian Archipelago", a region which corresponds roughly to present day Indonesia, the island portion of Malaysia, and part or all of New Guinea and Papua New Guinea.
The main distribution area of Hoya lacunosa. Populations of this species may occur farther northwest into northern Thailand and even into India, though present collected material does not bear this out. H. lacunosa is not thought to occur past Wallace's Line (D), nor in the Phillipines. A- Java, the site of the original collections of H. lacunosa var. lacunosa and var. pallidiflora. B- Langkawi Island, the site of Ed Gilding's small- leaved collection. C- southern Thailand, the source of H. lacunosa “Poonsak”.
VARIETIES, FORMS, AND CULTIVARS
As most Hoya growers will have noticed, hoyas can produce dramatically different foliage in response to differing cultural conditions. Hoya lacunosa is among the most marked species in the genus in this respect. Plants received from greenhouses will usually have small, succulent leaves with a teardrop shape, but the same plant in the lower light and humidity conditions of the general home environment will produce leaves that are twice as wide and long, and half as thick .
A) Hoya lacunosa var. pallidiflora, B) H. lacunosa var. lacunosa, C) H. aff. lacunosa from Langkawi Island. The bottom leaf of each pair is typical of growth produced in highlight, high-humidity conditions of a greenhouse. The upper leaf of each pair was produced from the same plant in lower-light, lower-humidity conditions typical of indoor cultivation.
Hoya lacunosa var. pallidiflora differs from the species type in having generally more lanceolate, longer (up to 7cm), darker green leaves with little or no silver speckling. The leaves are typically more acute at the base than var. lacunosa's. The flowers, despite the implication of the variety name (pallidiflora= "pale flowered”), are not noticeably paler than those of var. lacunosa's.
Hoya 'Sunrise' is a hybrid between Hoya lacunosa var. pallidiflora and Hoya obscura. The leaves are larger than in typical lacunosa clones and the flowers are flushed with pink. Hoya 'Sunrise' was produced by Michael Miyashiro.
Hoya aff. lacunosa from Langkawi Island has very small leaves, varying from 1 to 2.5cm. This plant was discovered on Langkawi Island (the largest island in an archipelago just west of the border of peninsular Malaysia and Thailand) by Ed Gilding during a trip with Torill Nyhuus and Ted Green in 1999. This plant has somewhat rounded corona apexes.
Hoya cv “Rebecca” is a cross between Hoya lacunosa Langkawi Island and Hoya obscura and it is created by Antone Jones. It is the product of a pollination by a moth/butterfly. Antone planted the seeds and chose the best seedlings.
Rebecca has a sister cultivar named, Rachel. According to Antone, they are from the same pod but the seedlings looked different so he gave them each a separate name and tossed the rest of the seedlings away. The leaves are 2.5-6 cm long and 1-2 cm wide and have very prominent veins. If this hoya is grown in very bright light/sunshine the leaves will get a lovely red colour. New leaves are often very red, but as they get older the red fades to only a nice red tone.
The almost ball shaped flowers are small, only 4-5 mm in diamater, lovely pink with yellow center. There are 20-30 flowers in each umbel and they last more than a week.The flowers will open 26-30 days from formation of floral buds.