Hoya Handbook

How we make this

This page explains where the information comes from, how it is turned into profiles and tools, and what we deliberately do not do.

Sources we use

In order of preference:

  1. Taxonomic databases. The World Checklist of Vascular Plants (WCVP, Royal Botanic Gardens, Kew) for accepted names, authorities, synonyms and native ranges; the International Plant Names Index (IPNI) for name records and publication details.
  2. Descriptions. Floras (for example Flora of China and Flora of British India), original species descriptions (protologues, often read on the Biodiversity Heritage Library) and peer-reviewed papers.
  3. Institutional horticulture. Botanic gardens and university extension services such as the Royal Horticultural Society, Missouri Botanical Garden, NC State Extension and NParks Singapore.
  4. Pet safety. Only the ASPCA Toxic and Non-Toxic Plants list.

We do not cite blogs, shops, forums or Wikipedia. We read them sometimes for leads, then go to the primary source.

Taxonomy and native range

Names and native ranges are pulled automatically from WCVP through the GBIF checklist API by a script in the site's code, so they are not retyped by hand. The current data was retrieved on 2026-09-30 from the WCVP release published 2026-06-04. Each profile links to the matching Plants of the World Online page, which shows the same WCVP data. Native ranges use the botanical regions of the World Geographical Scheme for Recording Plant Distributions (TDWG level 3), such as "Borneo" or "Assam".

Traits and measurements

Each profile records traits from a fixed vocabulary so that species can be compared and filtered. A trait is recorded only when a cited description supports it. Measurements (leaf length and width, flower diameter, flowers per umbel) are copied from the cited description with the source number next to them. If no source gives a value, the profile says "not published" instead of estimating.

Growth habit

  • Climbing, twining vine
  • Trailing or pendent
  • Shrubby, semi-upright

Leaf shape

  • Linear (narrow, strap-like)
  • Lanceolate (lance-shaped)
  • Elliptic (oval, widest in the middle)
  • Ovate (egg-shaped, widest below the middle)
  • Obovate (widest above the middle)
  • Orbicular (nearly round)
  • Obcordate (heart-shaped, notched tip)

Leaf texture

  • Thick and succulent
  • Leathery
  • Thin, papery
  • Hairy
  • Smooth (hairless)

Venation

  • Veins not visible
  • Lateral veins visible
  • Veins a different color from the blade
  • Many close, parallel side veins

Variegation

  • Plain green
  • Silver flecks (splash)
  • Variegated forms (cultivars) documented

Flower colour

  • White
  • Cream
  • Yellow
  • Orange
  • Pink
  • Red
  • Maroon
  • Purple
  • Green
  • Brown

Leaf size classes used by the identifier are derived from the cited length range: up to 5 cm, 5–10 cm, 10–20 cm and over 20 cm. The boundaries are inclusive, as the labels read: a leaf of exactly 5 cm is in both "up to 5 cm" and "5–10 cm", exactly 10 cm is in both "5–10 cm" and "10–20 cm", and exactly 20 cm is in "10–20 cm" only. A species belongs to every class its cited range touches, so a range of 2.5–5 cm counts as both "up to 5 cm" and "5–10 cm".

Leaf drawings

The leaf drawings are generated by code from each profile's recorded shape, venation, texture and size. When a leaf length is published, the drawing is to scale on a 1 cm grid: the solid outline is the largest cited leaf and the dashed outline the smallest. The outline itself is a schematic of the recorded shape, not a tracing of a real leaf. When no size is published, the drawing is marked as schematic.

Care guidance: species or genus

For most hoya species, no botanic garden or extension service publishes species-specific care instructions. Each profile therefore states its care basis. "Species" means a cited institution gives guidance for that taxon. "Genus" means the notes are general hoya guidance from institutional sources, sometimes combined with what the cited literature says about the plant's wild habitat. We never invent species-specific numbers.

Difficulty rating

The difficulty label is an editorial rating, not a measurement. It follows a fixed rule:

  • Easy: succulent or leathery leaves, and at least one institutional horticulture source covers the plant in cultivation.
  • Demanding: thin leaves, or a cited wild habitat of cool montane forest (roughly above 1,500 m) or permanently wet lowland forest, or an institutional source that calls it difficult.
  • Moderate: everything else.

Each profile gives the reason for its rating, with a source.

Pet safety

We report only what the ASPCA list states. Species it does not list are shown as "not listed by ASPCA", which is not a statement that they are safe.

AI-assisted drafting and review

Pages are drafted with AI assistance working from the cited sources, following the rules on this page. Every citation must point to a source listed on the page; the site's build fails if it does not. The publisher then reviews each page against its sources. Each page shows its status: "Reviewed" once that check is done, or "Not yet reviewed by the editor" before it. We do not claim to have grown, tested or photographed plants that we have not.

Dates

A page shows the date it was actually published on this site and, if it changed later, the date of the last substantive update. Pages are released in weekly batches; dates are never set in the past.

What we do not do

  • No invented measurements, experiences, reviews, testimonials, authors or credentials.
  • No copied text or photos; sources are paraphrased and linked.
  • No sponsored content or affiliate links.
  • No automatically generated pages without content (no tag archives or empty categories).

Corrections

Found an error? Tell us, with a source. We correct the page and update its date.