The Genus Schismatoglottis (Section Philonotion) in America

Abstract

The genus Philonotion Schott is included in Schismatoglottis, forming the American section of an otherwise Asian group. Two species are recognized in this section: 1) S. americana, known only from Surinam, and 2) S. spruceanum, here transferred from the genus Philonotion and represented by two varieties: var. spruceanum of Amazonian Venezuela and adjacent Colombia, and var. williamsii of Amazonian Venezuela only. GEORGE S. BUNTING, Missouri Botanical Garden, 2315 Tower Grove Ave., St. Louis 10, Missouri. The genus Philonotion was published by Schott (Gen. Aroid. 54. 1858.) to accommodate a single Spruce collection from Amazonian Brazil. For a century, this monotypic genus has been maintained and included in various works on the Araceae. Known from the type collection only, its alliance was variously interpreted. Schott (Prod. Syst. Aroid. 317. 1860.) judiciously placed Philonotion in the subtribe Adeloneminae immediately preceding subtribe Schismatoglottidinae. Engler (Pflanzenreich IV. 23(55): 24. 1912.) included it in the subtribe Philodendrinae following Philodendron. This latter treatment is curious, since that author noted the parietal placentation, the distinctive stamens with apical pores, and the nonscandent habit of growth of Philonotion. In contrast, placentation in Philodendron is axile, the stamens are of an entirely different nature, and the species are predominantly scandent. The deciduous nature of the blade of the spathe and staminate portion of the inflorescence after anthesis in Philonotion further differentiate these two genera. Philonotion falls clearly into the subtribe Schismatoglottidinae as defined by Engler (l.c. p. 24). Indeed it appears that Philonotion is the American section of the otherwise Malaysian genus Schismatoglottis.1 The first and only American species to be described in the latter genus is S. americana Jonk. & Jonk. Following its description (Acta Bot. Neer. 2(3):362. 1953.), the authors commented upon the apparent relationship between Philonotion and Schismatoglottis. The current study has verified the close affinity of these two genera, and has demonstrated clearly that S. americana is congeneric with material referred by other workers to Philonotion. Philonotion was initially characterized by a unilocular ovary bearing one parietal ovule. Recent collections that are undoubtedly conspecific with the type of this genus (P. spruceanum Schott) have either one or two parietal placentae each bearing one or two ovules, and the unilocular ovary may thus contain one to four ovules. The Malaysian Schismatoglottii commonly have ten or more ovules per ovary attached along three parietal placentae. With the exception of the fewer ovules, however, there is no constant floral character separating Philonotion from Schismatoglottis. Generally, an occasional staminode is found among the pistillate Issued March 31, 1960. 1Similar disjunction exists in other aroid genera. Homalomena is a predominantly Asian genus of about eighty species, six or seven of which occur only in America and have characters diverse enough to be considered as a separate section of the genus by Engler. A similar disjunction occurs in the genus Arisaema. One species of the otherwise American genus Spathiphyllum is native in Indonesia and the Philippines. (69) This content downloaded from 157.55.39.104 on Mon, 20 Jun 2016 05:34:41 UTC All use subject to http://about.jstor.org/terms [VOL. 47 70 ANNALS OF THE MISSOURI BOTANICAL GARDEN flowers in the latter genus, and some species have a sterile appendage of the spadix. The American species, previously referred to Philonotion, exhibit neither of these characteristics, but rather possess one outstanding vegetative feature apparently not found in any Asian species-the aristate or subcaudate apex of the leaf blade. Despite these differences, it seems prudent to reduce Philonotion to the rank of section under Schisrnataglottis.2 SCHISMATOGLOTTIS section Philonotion (Schott) Bunt. stat. nov. Philonotion Schott, Gen. Aroid. t. 54. 1858.