NOTE: This page was originally published in the Exotic Rainforest by Steve Lucas. After his passing away, the website was taken down, and the pages lost except for some archived pages in the wayback machine. In order to preserve Steve's work, I am republishing the page below in order that other people may continue to benefit from his writings.
Within our collection we have many species of Philodendron. If you are seeking other photos,
If the plant you believe is
doesn't look like this photo,
Philodendron williamsii Hook. f.
A member of Philodendron section Meconostigma, Philodendron williamsii is truly rare in both nature and collections. The photo above is of a plant in the collection of rare plant collector Ron Weeks in Miami, FL. This species has been the source of a great deal of confusion among collectors. Little information is available on Philodendron williamsii either in botanical journals or via the internet. The Missouri Botanical Garden's TROPICOS website map locator indicates the plant has been collected in areas of Central America. However, the Royal Botanical Garden Kew indicates the species was strictly collected in Brazil.
Here is an explanation for the confusion written by noted aroid expert Julius Boos, "The two species in question are very different, and occur naturally in different areas of Brazil, P. stenolobum in South-Central Brazil, P. williamsii further North-East in the tiny remnants of what used to be the Brazilian Atlantic Coast rain forest, now almost gone, bulldozed for cow pastures. They differ from each other in important sexual features, this can be read in Dr. Gonçalves paper in Aroideana. If you are interested in seeing a fantastic plant of true P. williamsii visit Silver Krome Nursery in Miami, FL and if Dennis Rotalante and his son Big Bill are able they can show you their plant of this, one of only five specimens in Florida (three in the Miami area, two, one misidentified as P. stenolobum, in W. Florida. I believe there are only seven specimens in the entire United States. They all came from Missouri Botanical Garden, grown from wild-collected seed in Brazil and were harvested by Dr. Simon Mayo of Kew Gardens in London. P. williamsii is now so scarce in the wild that Dr. Gonçalves in his search for wild specimens, while doing research for what was his description of P. stenolobum, came across only one plant growing high in a tree in a tiny remnant of the original forest. Graf's books Exotica and Tropica are now way out of date but there are still some 'old school' collectors who believe them just like, believe it or not, there is still a "Flat Earth Society", with members who swear that our Earth is flat."
The leaf blades of Philodendron williamsii are moderately coriaceous (leathery) and according to Aroids, Plants of the Arum Family can grow to 35 inches (90cm). However, the published scientific description of Philodendron williamsii indicates the blades are only 30 to 76cm (1 foot to 2.5 feet) in length. I fear much published non-scientific information, including that otherwise excellent text, may be actually describing Philodendron stenolobum Gonçalves in error since information simply does not match the scientific description of Philodendron williamsii. Philodendron stenolobum is also a member of Philodendron section Meconostigma but the two species are not interchangeable and are not from the same states in Brazil. You will soon read a note from the botanist who wrote the description of Philodendron stenolobum which echos that fear. In Brazil, P. williamsii is found on the Atlantic coast while Philodendron stenolobum is found only in the south central portion of Brazil. Aroid expert Leland Miyano explains, "Dr. Simon Mayo of KEW wrote the revision of the subgenus, Meconostigma in 1991. He did not split Philodendron stenolobum from Philodendron williamsii...but he did note the differences and thought that two taxa may be involved between the Espirito Santo state plants and the Bahia state populations. He did not have the fertile material of Philodendron stenolobum to compare."
At one time this species was popularly thought to be grown by collectors but the plant they were collecting is truly Philodendron stenolobum Gonçalves . The majority of plants offered for sale on the internet and called "Philodendron williamsii" are not the true species but are instead Philodendron stenolobum. P. stenolobum is highly variable with more than one blade form and as a result collectors often believe they have a very rare Philodendron williamsii in error. I include myself in that group! I now own two specimens of Philodendron stenolobum and until I began to research this article with the help of expert Julius Boos I was certain both were Philodendron williamsii. P. stenolobum often has several different blade shapes. The two species are vaguely similar but most collectors appear to believe P. stenolobum is the more beautiful of the two. With careful examination the differences can easily be seen. As a result, Philodendron williamsii is rarely seen in collections. Still, you can find many websites today identifying photographs of Philodendron stenolobum incorrectly as Philodendron williamsii. This link better explains natural variation which is a known scientific subject: .
The problem appears to have been caused by a variety of horticulturalists and/or collectors who have failed to read the scientific material describing both species. All too often horticulture differs from botanical science and grants plants names that are not scientifically accurate. In a personal letter to aroid authority and expert Julius Boos, Brazil's top aroid botanist, Dr. Eduardo Gonçalves, made this observation, "All horticultural "P. williamsii" is now P. stenolobum. The real P. williamsii is a completely different species, occurring in coastal Bahia state and is rather rare. I don´t have it in cultivation and I have never seen a living specimen in any collection I have visited. It looks like a P. speciosum (or like a huge P. corcovadense), but is somewhat smaller in overall dimensions. I have collected it twice in southern Bahia and I have seen a few more collections in Herbarium. Philodendron stenolobum is only known from Espirito Santo state and is much more common, being found by me in many different localities. I don´t know when or where the confusion began, but P. stenolobum is called P. williamsii in lots of old publications (including Graf´s Exotica). Simon in his revision of Philodendron Meconostigma included P. stenolobum specimens in P. williamsii, probably because he hadn´t enough good material of P. stenolobum to be sure it was a different thing."
Leland Miyano who lives in Hawaii explains in even more detail. Leland has lived and worked in Brazil alongside world renowned plant collector Roberto Burle-Marx, Leland wrote in April, 2008, "I think that a lot of the confusion of Philodendron williamsii, Philodendron spiritus-sancti, and Philodendron stenolobum arise out the geography of the area.
First of all, the name P. spiritus-sancti is derived from the state of Espirito Santo, Brazil. Philodendron spiritus-sancti is found near the town of Domingo Martins, Espirito Santo state, Brazil. North of this town is the town of Santa Leopoldina...a source of much confusion for a host of Philodendron horticultural names. Further to the north is the town of Santa Theresa....which is where the Augusto Ruschi Museum is. I do not know the exact limits of the distribution of Philodendron stenolobum , but we found it as we approached the region of the Rio Doce, in Espirito Santo state.
At the time, Philodendron stenolobum was thought to be Philodendron williamsii because Simon Mayo was actively working on Meconostigma. I met him at Roberto Burle-Marx's sitio before he published his treatment. In fairness to Simon Mayo, he had to work with only a few specimens and incomplete material. He also thought that the Espirito Santo state plants differed from the Brazilian state of Bahia population...which is where the true Philodendron williamsii is found. Bahia state is to the north of Espirito Santo state. Northern Espirito Santo and Southern Bahia have a really interesting floral link. To add to the confusion, Philodendron stenolobum has been referred in the horticulture trade as Philodendron 'Espirito Santo'."
The drawing to the right of the inflorescence of Philodendron williamsii is from Volume 28 of Curtis's Botanical Magazine, Royal Botanic Garden Kew
If after reading the explanations from Dr. Gonçalves and Leland you still believe you have Philodendron williamsii, please understand it is highly unlikely you actually have the species in a private collection. As reported by Leland, Philodendron specialist Simon Mayo of the Royal Botanical Garden Kew is reported to have collected Philodendron williamsii in Brazil in Bahia, Uruçuca, and Distrito de Serra Grande. And if you are still convinced you possess the species as I was prior to spending a great deal of time exchanging mail with Julius Boos, you can use Julius' expert information to easily discern the difference. According to Julius, a fool proof method to determine which species you possess is to look for the super-wide sinus with the near naked to the top vein of the rear lobes of Philodendron williamsii. If you are unaware of what a "sinus" is on a plant it is simply the area between the lobes. On Philodendron williamsii these are quite different from those of any form of Philodendron stenolobum. After suggesting growers compare the two species side by side, Julius wrote, "All these leaf variations in P. stenolobum still possess a much narrower sinus with only a short area of naked veins near the very base of the sinus".
In an effort to get the best information possible I requested additional notes from Dr. Gonçalves (gon-ZAL-ves) of the Universidade Catolica de Brasilia who is the most noted Brazilian botanical authority on Philodendron sp. and aroid species. Dr. Gonçalves published the scientific work on Philodendron stenolobum and responded in a personal email: "Philodendron williamsii is a hemiepiphyte and usually occurs very high at the canopy, sometimes above 30m above the soil. It is one of the rarest self heading Philos and I could collect it only a few times." A hemiepiphyte (hem-a-EPA-fit) is a species that may begin life either on the side of a tree as an epiphyte and extend its roots to the ground or it may begin life in the soil and grow up the tree to become epiphytic. In Dr. Gonçalves' response it becomes obvious this one can be quite a climber able to reach almost 100 feet into the canopy! However, recent information indicates this plant is not likely to climb to that height. Instead, it begins life up in the branches as a seed and drops roots all the way to the ground. A "self heading" species is one that is capable of standing upright alone without support. Dr. Gonçalves' email further indicated this species may be prone to rot.
Julius also provided the following information for those truly serious about determining exactly which species they possess, "In determining if a plant is P. williamsii or P. stenolobum, the following will be of help. The leaf ratios (length to width) are: P. williamsii, 1-1.5, P. stenolobum: 2.1-3.3. On leaf blades of P. williamsii the veins of the hind or posterior lobes of the leaf blade at the sinus (the "Y" at the top of the main lobe where the petiole attaches to the leaf blade) are around 50% 'naked' on their top sides, with only a small portion near the very tops of the posterior lobes with tissue on both sides of these veins. (see photos and the illustration of Hooker`s type.). In P. stenolobum there is only a short naked portion on the veins near the base of the "Y", less than 25 % of the length of these veins. (See photos and illustrations in Dr. Goncalves' paper.) As in all botanical specimens, the final proof is in the fertile material, and though most hobby-type growers may only infrequently have blooms on their plants, the following information is in fact the most important aspects of determining the differences between these two very different species. In P. williamsii, the gynoecium is 'barrel-shaped', and has up to 12 chambers or locules. (see Hooker`s illustration) In P. stenolobum, the gynoecium is 'flask-shaped and contains only 7-8 chambers or locules. (see Dr. Goncalves' illustration)."
But keep in mind, due to the extreme rarity of the actual species, it is highly unlikely you will find Philodendron williamsii, even by accident, in a private collection. Very few accredited botanical institutions actually possess a true specimen. Almost all plants sold with this name are actually a form of Philodendron stenolobum.
Philodendron species, and especially hybrid forms, are known to be highly variable and not every leaf of every specimen will always appear the same. This link explains in greater detail the scientific principle of natural variation and morphogenesis.
From Curtis's Botanical Garden, Volume 28
Native of Brazil.
Nat. Ord. AROIDE^E.•Tribe PHILODENDREIE.
Genus PHILODENDRON, Schott ; (Prod. Syst. Aroid., p. 219).
PHILODENDRON WiUiamsii ;
trunco crasso suberecto cicatricato, foliis longe
petiolatis 2-3-pedalibus ¡sagittatis acutis lobis posticis
oblongoovatis obtusis, costis venisque subtus lu ride
rubro-purpureis, costis loborum posticorum basin versus sinus
marginalibus, venis patentibus, venulis numerosissimis, petiolo
elongato terete lsevi supra canliculato, pedunculis solitariis
axillaribus spatha viridi intus
This noble Aroid has been for years a well known ornament of the aquarium near the Palm House at Kew, growing in a pot the base of which is immersed, and forming a crown of bright green foliage, six feet in diameter, and four to five feet in height. It was sent to Kew by Mr. Williams, of Bahia, many years ago, flowers annually, and would have been published in this Magazine ere this, but for the difficulty of naming the plants of this genus, which embraces upwards of one hundred and fifty species, many of them most imperfectly described. As however it agrees with none of those contained in Schotte excellent monograph (1800), has not since been figured in any publication accessible to me, and has not been recognised by the many continental botanists and horticulturists who have seen it at Kew, I am emboldened to describe it as new, and give it the name
MAT 1ST, 1871.