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Hoya Overview

A Brief Overview of Hoyas

Hoya is a genus of tropical plants in the dogbane family, Apocynaceae. Native countries include: Philippines, India, Thailand, Malaysia, Vietnam, Bangladesh, Indonesia, Polynesia, New Guinea, and Australia. The genus was named by botanist Robert Brown, in honor of his friend and botanist Thomas Hoy.

Hoyas are evergreen perennial creepers or vines, and sometimes shrubs. In the wild they are often found growing epiphytically on trees. They climb by twining and with the help of aerial roots. They all have simple entire leaves arranged in an opposite pattern, but they may be smooth, felted, or hairy with or without prominent venation. It's also very common for the leaf surfaces to be flecked with small silvery spots, known as "splash" in the Hoya community. Since the Hoya is related to the milkweed plant, all Hoyas produce a milky white sap that can be irritating to the skin.

Although Hoyas produce beautiful foliage, many people collect them for their remarkable flowers. All Hoya flowers are shaped like five-pointed stars. Most grow in umbels, or singly in some species. The flowers come in all sizes, scents, and colors. It can take years for a plant to flower, but once it does the blooms will grow back on the same spurs for years to come, which makes it very important to not clip the peduncles from the plant. It's also worth noting that Hoyas will put out long, bare vines before the leaves show up on them. Many new growers find these strange and simply clip them off, but it's just the way Hoyas grow. Trust the process!

If you are interested in learned more about Hoyas, The Hoya Handbook has lots of basic information for new growers.

Writing & Naming Hoyas

Some Hoya names are simple while others can contain abbreviations and letters that are confusing to many people. Here, I will walk you through the basics or writing and naming Hoyas.

The Basics

To make naming cohesive and universal, there is an international system for naming plants that is used by scientists and plant professionals, known as the International Code of Botanical Nomenclature." It is based on a binomial (two-name) system. Each plant is given a "first and last name" generally based in Latin, that is unique to each species. The scientific name of a plant consists of two names:

  1. The genus or generic name
  2. The specific epithet or species name

When writing these names, it is important to adhere to a specific set of rules. These include:

  • The genus is written first, and the first letter is always capitalized.
  • The genus & species should be underlined or italicized.
  • The epithet or species is written second and is NOT capitalized.

Example: Hoya ilagorium

Mutations

Plants are constantly evolving, which means mutations are constantly occurring. Mutations can show up as a change in color, size, or growth habit. These characteristics are passed on to the individuals offspring. When this happens, we get what we call a sub-group. If the mutated group is significantly different from the parents and the traits are passed on from generation to generation, then this new group is typically assigned a variety name.

ssp. = subspecies, which notates a subspecies of a particular species. For example, a subspecies of Hoya australis would be written like this: Hoya australis ssp. oramicola.

var. = variety. Variety names are given when a mutation occurs in nature. 

Example: Hoya imperialis var. rauschii

Mutations can also occur because of human interference. In this case, the group of mutated plants is called a cultivar. Cultivar is an abbreviated form of cultivated variety. 

Examples: Hoya carnosa x Hoya serpens cv. Shok -OR- Hoya carnosa x Hoya serpens 'Shok'

"aff." and "sp. aff."

We often see these abbreviations used in Hoya names and it's important to understand why they are used.

sp. aff.species affinis, which is a taxonomic term used in botany. It indicates that available evidence suggests the species is related to, has an affinity to, but is not identical to, the species with the binomial name it comes before. A common one we see a lot is Hoya sp. aff. burtoniae -- this plant has many similarities to Hoya burtoniae, but is not, in fact, a TRUE H. burtoniae.

To use aff. alone implies that the specimen differs suggestively from the holotype but that further progress is necessary to confirm that it is a novel species.

You can read more about nomenclature here and here.

To learn how Hoyas are given their names, check out this blog post by hoya-obsession.com.