MODERN WORK

Since no revisionary work took place on Philodendron since the time of Krause and before the advent of George Bunting's revisionary work, most species were described as the result of floristic work and most of these were from South America. In all 142 new species epithets for Philodendron have been introduced to date since the time of Krause's revision (including 5 species published by Grayum in 1992). In addition 11 new varieties, seven new subspecies and one form were published during this period. A total of six new combinations were made. Of this total only 33 species of Philodendron were reported for Central America and 11 of these were in P. subg. Pteromischum. Thus a total of 22 species of P. subg. Philodendron were published between the last ful revision of the genus by Krause and the completion of the current work (not including those species of P. subg. Pteromischum in Grayum (1996). A list of the taxa of P. subg. Philodendron described between the time of Krause's revision and the completion of this work is listed below:

Philodendron apocarpum Matuda = P. jacquinii Schott

Philodendron auriculatum Standl. & L.O. Williams

Philodendron basii Matuda

Philodendron brenesii Standl.

Philodendron davidsonii Croat

Philodendron dressleri G.S. Bunting

Philodendron erlansonii I.M. Johnst. = P. jacquinii

Philodendron glanduliferum Matuda

Philodendron harlowii I.M. Johnst. = P. hederaceum

Philodendron jamapanum G.S. Bunting = P. sagittifolium Liebm.

Philodendron jodavisianum G.S. Bunting

Philodendron lancigerum Standl. & L.O. Williams = P. sagittifolium

Philodendron latisagittatum Matuda = P. mexicanum

Philodendron lundellii Bartlett ex Lundell = P. jacquinii

Philodendron microstictum Standl. & L.O. Williams

Philodendron miduhoi Matuda = P. hederaceum

Philodendron mirificum Standl. & L.O. Williams = P. pterotum K. Koch & Augustin

Philodendron monticola Matuda = P. advena

Philodendron platypetiolatum Madison

Philodendron pleistoneurum Standl. & L.O. Williams = P. grandipes K. Krause

Philodendron pseudoradiatum Matuda = P. radiatum var. pseudoradiatum (Matuda) Croat

Philodendron trisectum Standl. = P. anisotomum

Philodendron apocarpum Matuda = P. jacquinii

Philodendron auriculatum Standl. & L.O. Williams

Philodendron basii Matuda

Philodendron brenesii Standl.

Philodendron davidsonii Croat

Philodendron dressleri G.S. Bunting

Philodendron erlansonii I.M. Johnst. = P. jacquinii

Philodendron glanduliferum Matuda

Philodendron harlowii I.M. Johnst. = P. hederaceum

Philodendron jamapanum G.S. Bunting = P. sagittifolium

Philodendron jodavisianum G.S. Bunting

Philodendron lancigerum Standl. & L.O. Williams = P. sagittifolium

Philodendron latisagittatum Matuda = P. mexicanum

Philodendron lundellii Bartlett ex Lundell = P. jacquinii

Philodendron microstictum Standl. & L.O. Williams

Philodendron miduhoi Matuda = P. hederaceum

Philodendron mirificum Standl. & L.O. Williams = P. pterotum K. Koch & Augustin

Philodendron monticola Matuda = P. advena Schott

Philodendron platypetiolatum Madison

Philodendron pleistoneurum Standl. & L.O. Williams = P. grandipes K. Krause

Philodendron pseudoradiatum Matuda = P. radiatum var. pseudoradiatum (Matuda) Croat

Philodendron trisectum Standl. = P. anisotomum Schott

Three additional epithets were described in Philodendron but they were actually other genera, namely P. armigerum Standl. & L.O. Williams = Syngonium armigerum (Standl. & L.O. Williams) Croat, P. brevinodum Standl. & L.O. Williams = Monstera tuberculata Lundell var. brevinodum (Standl. & L.O. Williams) Madison and P. hastiferum = Syngonium hastiferum (Standl. & L.O. Williams) Croat.

Many of the remaining taxa in Krause's revision were synonymized or reduced in rank and only 11 taxa in P. subg. Philodendron remained. These were P. brenesii Standl., P. radiatum var. pseudoradiatum (Matuda) Croat, P. auriculatum Standl. & L.O. Williams, P. microstictum Standl. & L.O. Williams, P. basii Matuda, P. glanduliferum Matuda, P. dressleri G.S. Bunting, P. jodavisianum G.S. Bunting, P. platypetiolatum Madison, P. davidsonii Croat, and P. strictum G.S. Bunting.

Most of the Central American floristic work outside of Mexico was carried out by Paul C. Standley, often working with his associate Louis O. Williams. Standley worked initially at the Smithsonian and later at the Field Museum in Chicago, then finally terminating his career and dying in Honduras at Zamorano while working at the herbarium of the Escuela Agricola Panamericana. Standley described P. brenesii and P. trisectum (= P. anisotomum Schott) alone and with L. O. Williams he also provided the following epithets: P. armigerum (= Monstera armigerum (Standl. & L.O. Williams) Croat), P. auriculatum, P. brevinodum (= Monstera tuberculata Lundell var. brevinodum (Lundell) Madison), P. hastiferum (= Syngonium hastiferum), P. lancigerum (= P. sagittifolium), P. microstictum, P. mirificum (= P. pterotum), and P. pleistoneurum (= P. sagittifolium). It is unusual that despite the fact that there were many undescribed species of Philodendron subg. Philodendron in Costa Rica and Panama, these workers did not succeed in describing many of them since of the nine described, three proved to be other genera, and three others proved to be synonyms of existing Philodendron names. This is particularly surprising since both Standley and L. O. Williams were astute observers who were very familiar with the Central American flora in general. Their mistakes point out the complexity of the taxonomy of the Araceae and the bewildering array of material available to them at that time. Even when I began my own work with the Araceae in the late 1960s there were few specimens (aside from types) which proved to have the correct name. Specimens were often poorly preserved and inadequate and virtually all lacked good field notes. Either field observations or well prepared field notes describing aspects of the plants which are not available on dried plants are essential to the proper understanding of Philodendron and other Araceae. I believe that it is possible that this confusion, coupled with the dearth of well-prepared specimens and the paucity of types of Araceae, discouraged workers from making decisions about which species were new.

Perhaps owing to the difficulty with the genus, local floras in Central America were often inadequately done, even if one considers that fewer specimens were available to the authors than today. The treatment of the Flora of Panama (Standley 1944), for example, is woefully inadequate considering the small percentage of the total aroid flora that is covered compared to what is now known to exist.

In his treatment of some genera Standley (1944) seemed too willing to accept epithets of species described in Colombia, regardless of how well they "fit" Panamanian species. As a result many species names in genera such as Anthurium, for example, were wrong. His treatment of Philodendron subg. Philodendron was much better from the standpoint of correct names but he treated only eight of the 104 taxa (7%) of Philodendron subg. Philodendron now known for Panama. Only one species, P. hoffmannii (now P. jacquinii) had the wrong name. It was also misapplied, being intended for P. hederaceum. The other species he included in the Flora of Panama were: P. brenesii, P. brevispathum, P. grandipes, P. panamense, P. radiatum, P. tripartitum, and P. wendlandii. He did not do so well with members of P. subg. Pteromischum where P. karstedianum Schott was a mixture of two species and P. guttiferum was a mixture of three species. Perhaps the most curious thing about Standley's Flora of Panama treatment is that by 1944, after Robert Woodson and his collaborators had already made several expeditions to Panama, so few of the new species that are included in this revision had been collected. Paul C. Standley had collected some of the new species but failed to recognize them as new. These included: P. crassispathum Croat & Grayum (Standley & Valerio 51910), P. findens Croat & Grayum (Standley & Torres 52355), P. purulhaense Croat (Standley 89902), and P. strictum (Standley 51371). See discussion of those species for additional details. See also section on "Collecting History of P. subg. Philodendron".

The Flora of Guatemala (Standley & Steyermark, 1958) was much more accurate and complete in the percentage of the total taxa of P. subg. Philodendron which were included. However this probably has less to do with the fact that it was published 14 years later than it does with the fact that there are fewer, generally more widespread species occurring there than in Panama. The Flora of Guatemala treated 11 species of Philodendron, only 8 of them being members of P. subg. Philodendron. These were: P. anisotomum, P. hederaceum, P. hoffmannii (= P. jacquinii), P. radiatum, P. sagittifolium, P. smithii, P. tripartitum, and P. warszewiczii. With 50% of the present total taxa and with all but one of the names still properly named, the treatment remains generally more useful than that of the Flora of Panama. Added to the flora since the revision are: P. advena, P. fragrantissimum, P. glanduliferum, P. jodavisianum, P. mexicanum, P. purulhaense, and P. verapazense.

The Flora of Guatemala treated P. hederaceum correctly. They treated P. jacquinii as its synonym, P. hoffmannii. Curiously however, the illustration used represents both species. The leaf and stem seem clearly to be P. hederaceum but the inforescence clearly shows the long-protruded styles of P. jacquinii.

Standley's treatment of the Araceae of Costa Rica (Standley, 1937) was reasonably good, partly owing to the fact that many species were described by Schott from collections made by H. Wendland in Costa Rica. Other widespread species, whose taxonomy had been well established were also a part of the flora. Properly named Costa Rican species recognized by Standley were: P. brenesii, P. ligulatum, P. pterotum, P. radiatum, P. schottianum, P. tripartitum, P. verrucosum, and P. wendlandii. Species that are now synonymized include: P. gracile (= P. tenue), P. hoffmannii (= P. jacquinii, P. pittieri (= P. hederaceum), P. trisectum Standl. (= P. anisotomum). It has never been determined which species he included under the name P. panamense but that species is not known for Costa Rica. Thus with 8 out of the 13 names correct and with 3 additional species that at least represent synonyms of currently recognized species, Standley did pretty well (at least in comparison to the Flora of Panama treatment). However, with only 13 of the current total of 49 species treated (26%), the treatment was no more complete than that of the Flora of Panama which was written a few years later.

Though no other floristic taxonomist had such a prominent role with Central American Philodendron as Standley, there were others who described Philodendron during the course of their floristic work.

Ivan M. Johnston of the Arnold Arboretum described Philodendron erlansonii (= P. jacquinii) and P. harlowii (= P. hederaceum) while working on the flora of San José Island (Johnston, 1949) of Panama.

In Mexico, Eizi Matuda, the local aroid specialist, described seven species (Matuda, 1954): P. apocarpum (= P. jacquinii), P. basii, P. glanduliferum, P. latisagittatum (= P. mexicanum), P. miduhoi (= P. hederaceum), P. monticola (= P. advena), and P. pseudoradiatum (= P. radiatum var. pseudoradiatum), and George Bunting described four species during his investigations of Mexican Araceae (Bunting, 1965), P. dressleri, P. jamapanum (= P. advena), P. jodavisianum, and P. tuxtlanum G.S. Bunting (= P. sagittifolium).

Matuda's treatment of the Philodendron in Mexico (Matuda, 1954) dealt with 16 species, 13 of them in P. subg. Philodendron

While a number of the species had the correct names, e.g., P. advena, P. mexicanum, P. pseudoradiatum, P. radiatum, and P. tripartitum. Others were named with correct synonymous names, e.g., P. sanguineum and P. daemonum (both currently recognized as P. sagittifolium). Matuda also recognized P. mexicanum under three different names, namely P. mexicanum, P. latisagittatum, and P. sagittifolium (a distinct species that he treated as both P. daemonum and P. sanguineum (a currently recognized name improperly used - see above). Matuda redescribed two previously described species using the names P. apocarpum and P. miduhoi (currently P. jacquinii and P. hederaceum respectively). Finally he described P. monticola (now also considered P. advena).

Other Central American species of P. subg. Philodendron published since the time of Krause's revision and prior to the beginning of this specific project in 1986 include: P. davidsonii and P. platypetiolatum, the latter described from Ecuador during Mike Madison's extensive work with the flora of Ecuador during his tenure at the Selby Botanical Garden. Thus, up to the time of the initiation of this current study only 26 species in P. subg. Philodendron were described for Central America. With 96 species of P. subg. Philodendron now known for Central America, (Appendix 3, Hierarchical List of Nomenclatural Priority in Central American Philodendron), this registers an increase of 70 species or a 270% increase.

Of the species of P. subg. Philodendron described since Krause's revision (not including the present effort) only 2 were described by non-specialists (both by I. M. Johnston). This assumes that Paul C. Standley, who described the bulk of the new species, can be considered an aroid specialist. Since he described most of the new Central American species and wrote most of the floristic treatments of the Araceae for Central America, he should be considered a specialist. Despite this, I don't believe that Standley fully understood the diversity of the Araceae. This is because he failed to recognize a relatively large number of species that were new to science. In Standley's defense it must be stated that the Araceae is a particularly complex family with so much interspecific variation that proper decisions often cannot be easily made without direct comparisons of living material. In addition, collections in the past often had few or no field notes to use for study.