Monographs Details: Ixora graciliflora Benth.
Authority: Maguire, Bassett. 1967. The botany of the Guayana Highland--Part VII. Mem. New York Bot. Gard. 17: 1-439.
Family:Rubiaceae
Description:Distribution and Ecology - French and British Guiana, and Suriname. FRENCH GUIANA. Along road toward Cayenne, ca 15 km from St. Laurent, Cowan 38933. SURINAME. Corantyne River, Wonotolio, Stahel & Gonggrijp 2547 (type of Ixora surinamensis) ; Nassau Mts., Marowijne River, in forest on ferrite, Plateau A, 1 km E of Camp I on Line A, alt 430-520 m, Cowan & Lindeman 39031; Joden Savanne-Mapanecreek area, rainforest near Kamp B, Kramer A Hckking 2886; along bank of Marowijne River, opposite Sparonini, Lanjouw & Lindeman 3455. BRITISH GUIANA. Twasinki Falls, basin of Essequibo river, lat about 5°5'N. 28 Sep 1937, A. C. Smith 2141 (type of I. xantholoba) ; Schomburgk 202 (type of Siderodendron laxflorum); wallaba forest, mile 96, Bartica-Potaro road, upper Mazaruni River, Pakaraima Mts., alt 100 m, Maguire & Fanshawe 32147; Fauta forest in gorge, Membaru-Kurupung trail, alt 1000 m, Maguire & Fanshawe 32406; Wabuwak, Kanuku Mts., rain forest, alt 600 m, Forest Dept Field No. TUB 278, 200; Takutu Creek, to Puruni River, Mazaruni River, Forest Dept Field No. Fanshawe 2016; forest along cattle trail, along the Berbice-Rupununi Cattle Trail, Berbice or Demerara County, Abraham 247; Schomburgk 202 (photo of type of Ixora graciliflora from K at NY)

Discussion:

Ixora surinamensis Brem., Rec. Trav. Bot. Neerl. 3: 273. 1934.

Ixora xantholoba Standley in A. C. Smith, Lloydia 2: 215. 1939.

Siderodendron laxiflorum Benth., Jour. Bot. Hook. 3: 235. 1841, non Ixora laxiflora Sm. in Rees, Cycl. 19, no. 8. 1811.

Type. British Guiana, Schomburgk 202.

In his description of Ixora xantholoba, Standley describes the hypanthium as glabrous. A study of the holotype and isotype collections shows the hypanthium to be minutely puberulent without, as it is in the type collection of I. surinamensis and I. graciliflora.

At first it would appear that the axillary inflorescences found in I. surinamensis would indicate a species distinct from I. xantholoba and I. graciliflora, in which the inflorescences are mainly terminal. Examinataion, however, of additional material of I. surinamensis and I. xantholoba shows that both axillary and terminal inflorescences and infructescences may occur on the same branch of the specimen, as indicated by Maguire & Fanshawe 32147 and Fanshawe 2016 from British Guiana, Sowan 38933 from French Guiana, and Cowan & Lindeman 39031 from Suriname.

The size of the inflorescence, likewise, is variable, from a long-branched, axillary type as exemplified by Forest Dept. WB 378 from British Guiana, simulating the holotype of Ixora surinamensis, to a short, terminal inflorescence type manifest in the type collection of I. xantholoba. The holotype of I. xantholoba at F shows a terminal, much reduced inflorescence lacking a common peduncle, whereas the isotype at US shows a longer, more branched inflorescence with a common peduncle about 10 mm long. The specimen, Fanshawe 2016, from British Guiana has only an axillary inflorescence on the US sheet, a terminal inflorescence only on the NY sheet, whereas both types are present on the F sheet! The prominent elevated lateral nerves of the lower leaf-surface in this collection number matches the same prominent nervation found in the specimen of Forest Dept. WB 378.

In various other characters, moreover, it is found that Ixora surinamensis cannot be distinguished from I. xantholoba. Both have the following characters in common: (1) the style is puberulent in the lower portion, but glabrous from the middle to the summit, a character not encountered in other species of Ixora examined; (2) puberulent peduncle and branches of the inflorescence; (3) puberulent hypanthium and calyx; (4) same size of hypanthium and calyx; (5) same shape of calyx-lobes and bracteoles; (6) same puberulence and size of corolla-lobes; (7) same type of puberulence on upper part of stem; and (8) prominent lateral nerves on the lower leaf-surface. A comparison of these characters indicates that only one taxon is represented, varying only in the relative size, branching, and position on the stem of the inflorescence.

Distribution:French Guiana South America| Guyana South America| Suriname South America|