Hoya krohniana Kloppenb. & Siar

Natural Habitat

Kew accepts krohniana separately and lists the Philippines as native, with a primarily wet tropical biome. This broad account does not establish a particular island, elevation, host tree or substrate.

Publication and naming history

Kloppenburg and Siar published the name in Fraterna 22(4), pages 9–12. They designated specimen 70365 at CAHUP as the type: the reference specimen associated with the name. This page has checked the published citation, but has not independently examined that specimen.

The account says the flowers came from Cindy Krohn and that the plant was thought to be Philippine. It names the species for her late husband Phillip, who had obtained the plant. That cultivated history does not supply a precise wild collection locality.

The authors compared it with lacunosa using flower-stalk length, flattened corolla diameter and corona dimensions. Their discussion also mentions herbarium sheets with similar leaves, while explicitly leaving some determinations uncertain. Those sheets need examination; similar leaves alone do not turn them into verified krohniana records.

Historical names explained

Vermont Hoyas describes a plant received under the label heart-leafed lacunosa and later discussed as krohniana. That is a record of one grower’s label history, not the name of a newly established form.

Chamberlain (2021) reported consistently heart-shaped leaves in his material and questioned some other plants circulating as krohniana. Chamberlain (2024) still described his own identification as probable. Leaf shape alone does not independently settle the species or identify another cutting.

The plant, leaves and flowers

Kloppenburg and Siar (2009) describe small, opposite, deep-green leaves with a heart-shaped outline in their original cultivated material.

The flowers have hairy, rolled-back petals. The original description gives a flattened corolla diameter of 1.20 cm; that is a measurement with the petals flattened, rather than the natural spread of every flower.

The later leaf study, discussed below, found several leaf-base shapes in one cultivated plant labelled krohniana. Leaf shape and flower measurements must retain their source and material context; neither alone authenticates another plant.

What the leaf study establishes

Scott and Buot examined thirty fully expanded leaves from each of three cultivated plants labelled lacunosa, krohniana and pubicorolla. The krohniana material came from a garden in Kalayaan, Laguna; this is a cultivation source, not a wild locality. The authors did not verify the plants’ identifications with vouchers.

In the krohniana sample, leaf bases included convex, rounded and heart-shaped forms. The lacunosa sample lacked a heart-shaped base, but some other characters overlapped. These observations describe the sampled plants; they do not establish a rule for every plant bearing either name.

The measured venation characters gave limited separation, and the preparation method prevented a full examination of higher vein orders. The authors discussed possible closer relationships, but did not establish synonymy, authenticate cultivated clones or provide a universal identification key. See the <a href="/articles/hoya-lacunosa-and-krohniana/">lacunosa–krohniana comparison</a> for the measured leaf ranges and their limitations.

Limits of the locality evidence

A garden location in a leaf study and the probable Philippine origin in the description are different kinds of evidence. Neither should be plotted as a verified wild occurrence or translated directly into indoor temperature, light or watering instructions.

What would improve identification

The next evidence needed is the cited CAHUP specimen and its full label, traceable living accessions connected to the original material, and repeatable flower and leaf observations. The existing historical specimen and nomenclatural questions remain open; Kew’s accepted treatment is reported here without claiming an independent ruling on every earlier objection.

Keep a cultivated plant’s received label, acquisition source and propagation history together. Leaves, flowers and measurements from the same documented accession can support comparison. A trade label or a resemblance to one picture does not establish identity.

Observations of cultivated material

The older grower account describes scent and flowering after relocation; Chamberlain (2014) describes hanging growth and winter flowering in his house. These are observations of his cultivated material. They do not establish distinct care requirements or a general flowering schedule.