Strobilanthes alternata (Burm.f.) Moylan ex J.R.I.Wood
Purple waffle plant · Red ivy · Red flame ivy
- Family
- Acanthaceae
- Native to
- Known wild only as a cultigen from eastern Malesia
- Habit
- Creeping perennial
- Also known as
- Hemigraphis alternata (Burm.f.) T.Anderson, Ruellia alternata Burm.f.
Where it comes from
Almost nowhere, and that is the interesting part. Kew’s native range for this species reads “as a cultigen from E. Malesia”, with Maluku the only native region — while Java, Malaya, Sumatra, New Guinea and the Philippines are all listed as introduced.1 Which is why nobody can point you at a wild population: it may not really have one.
It travels well, though. It is recorded as invasive in eleven territories — the Dominican Republic, Hawai’i, Fiji, the Chagos archipelago, Réunion, the Cook Islands, Samoa, French Polynesia, Niue, Palau and Tonga — where it forms “large dense carpets that totally cover the understoreyunderstoreyThe layer beneath the forest canopy: dim, still and humid, lit mostly by sunflecks. It is the habitat nearly every houseplant comes from.Glossary of natural forests”, spreading mainly through dumped garden waste.2 In Florida it is naturalisednaturalisedGrowing and reproducing outside cultivation in a place it is not native to, without help. Three plants in this collection are naturalised somewhere, and banned there for it.Glossary in Miami-Dade but is not on the state’s invasive-species list; I checked the current Category I and II list and the watch list and neither genusgenusThe rank above species: a group of species close enough to share a name. Monstera and Philodendron are genera; the first word of a botanical name is the genus.Glossary appears on either.345
Naming and description
The genusgenusThe rank above species: a group of species close enough to share a name. Monstera and Philodendron are genera; the first word of a botanical name is the genus.Glossary on your label is gone — but not in the way it is usually told. Kew still accepts Hemigraphis as a genusgenusThe rank above species: a group of species close enough to share a name. Monstera and Philodendron are genera; the first word of a botanical name is the genus.Glossary, with 31 accepted species.6 What has changed is that your plant is no longer in it: Hemigraphis alternata is now a synonymsynonymA botanical name that is no longer the accepted one for a plant, usually because the same species was described twice. Old books and plant labels are full of them.Glossary of Strobilanthes alternata.17
The combination is J. R. I. Wood’s, validating a name attributed to Moylan, in Novon 23: 389 (2014),89 resting on a 2004 phylogenetic study of the group.10 The transfer is still going on — fourteen more Hemigraphis species moved across in 2019.11 NC State has already renamed its entry, keeping the old name as “previously known as”.12
Fun facts
- It really does strip volatile organic compounds out of air — and the caveat is the whole story. A 2009 screen of 28 ornamental species against five VOCs found this plant had the highest removal efficiency for four of the five, and named it one of five superior species.13 That result is real and it is almost always quoted without the conditions: six hours, in sealed containers, normalised by leaf area. It is a measurement of what a leaf can do, not of what a plant does in a room with a door — which is the same trap the snake plant’s NASA claim falls into elsewhere on this site.
- It cannot really reproduce except by being broken up. Outside its native range it appears to spread by cuttings and clump division only.2 Which explains both how easy it is to propagate on a windowsill and how it becomes a weed: every discarded fragment is a new plant.
- The ASPCA’s “Waffle Plant” page names a species that does not exist. Its scientific-name field reads Hemigraphis exotica — and a search of both Kew and IPNIIPNIThe International Plant Names Index. It records where and when a name was published, without ruling on whether it is the accepted one — that is POWO's job.Glossary returns zero results for that name, because ‘Exotica’ is a cultivarcultivarA plant selected and propagated by people rather than described from the wild. Written in single quotes after the species — Monstera deliciosa 'Thai Constellation' — and never italicised.Glossary epithetepithetThe second word of a botanical name — the deliciosa in Monstera deliciosa. It belongs to the species, and it never stands on its own.Glossary that someone promoted to species rank.141516 That is the sixth consecutive group in which an ASPCA plant page has not said what it appears to say.
Care
- Light
- Bright indirect. NC State's structured field says full sun but its own prose says direct sun bleaches and burns — follow the prose.
- Water
- Evenly moist, never waterlogged. Indoors it fails by sitting wet and losing its colour rather than by drying out.
- Humidity
- No figure is published for it by any extension service. High humidity suits it; that is as precise as the record gets.
- Temperature
- Warm. It dies below about 50 °F (10 °C), which is the practical floor.
- Substrate
- An ordinary free-draining potting mix. Nothing special is documented.
- Fertilizer
- Not documented at extension level for this plant. A balanced feed at half strength in growth is the conventional approach and this record does not dress it up as sourced.
- Propagation
- Cuttings or clump division, and that is effectively the only route — outside its native range it appears to reproduce vegetatively only.
- Dormancy
- Not documented. Nothing describes a rest period.
- Common problems
-
- Loss of the purple as light drops — the colour is the first thing to go and the earliest warning
- Rot in a mix kept wet, which indoors is the commonest way to lose it
- Bleached or scorched leaves in direct sun
- Cold damage below 50 °F (10 °C)
- Do not compost it outdoors in a warm climate: it spreads mainly through dumped garden waste and forms dense carpets that blanket forest understoreys