Cephalanthus salicifolius Bonpl. (Humboldt and Bonpland 1809: 63)

Romero, Maria Florencia, Gonzalez, Ana Maria & Salas, Roberto Manuel, 2023, Sylvainia, a new monospecific genus within the subtribe Cephalanthinae (Rubiaceae, Naucleeae), Plant Ecology and Evolution 156 (1), pp. 85-111 : 85

5. Cephalanthus salicifolius Bonpl. (Humboldt and Bonpland 1809: 63)

Figs 8 , 9

Cephalanthus occidentalis var. salicifolius (Bonpl.) A.Gray ( Gray 1884: 29) - Type: same as for Cephalanthus salicifolius .

Cephalanthus occidentalis subsp. salicifolius (Humb. & Bonpl.) Borhidi & Diego ( Borhidi and Diego-Peréz 2008: 75) - Type: same as for Cephalanthus salicifolius .

Cephalanthus peroblongus Wernham ( Wernham 1917: 176) - Type: MEXICO • Tepic; 31 May 1837; Barclay 1193; holotype: BM [BM000606674]; isotype: US [US00130642].

Type.

MEXICO • Crescit juxta Acapulco Mexicanorum, in calidis; Bonpland s.n.; holotype: P [P00135084].

Description.

Shrub or tree up to 6 m tall, much-branched. Stems glabrous, sparsely cover with lenticels. Leaves 2- or 3-verticillate, pseudopetiolate, pseudopetiole glabrous or puberulous, 1-10 mm long; blades narrowly ovate or linear-elliptic, glabrous, base acute, apex acute or acuminate, with a dark colleter at the apex when young, discolorous, 3-14 × 0.6-3 cm; principal lateral veins 8-10 on each side, leaf domatia present as tufts of hair; stipules broadly triangular, tardily deciduous, dark colleters present on the apex and margins, light colleters at the ventral (inner) side, intermingled with numerous trichomes. Inflorescences pedunculate, peduncle 2-5 cm long, bracteate, bracts foliaceous, with dark colleters at the apex and margins, bracteoles spatulate, puberulous, with dark colleters at the apex. Flowers perfect; calyx 4(-5)-lobed, hypanthium cupuliform, glabrous to densely pubescent at the base, 1.7-2.5 mm long, lobes oblong or rounded, pubescent on the external (dorsal) face, densely hairy on the internal (ventral) face, with dark colleters at the apex of the lobes, 0.3-0.6 mm long; corolla hypocrateriform, 4(-5) lobed, 5-12 mm long, on the external side with dark colleters at the interlobular sinuses, lobes obtuse to ovate, internally with a pubescent band, externally glabrous; 0.8-1.5 mm long, tube internally and externally glabrous; stamens 4(-5), filaments filiform, glabrous, anthers subsessile, sagittate; ovary 2-carpellate, 2-locular, each locule 1-ovulate; style filiform, 3-6 mm long; stigma capitate and exserted at flower maturity. Fruits obpyramidal or turbinate, pubescent, 4.5-5 mm long. Seeds 1.2-2.2 mm long; aril 1.5-1.8 mm long.

Distribution.

Cephalanthus salicifolius occurs in El Salvador, Honduras, Mexico (Colima, Chihuahua, Coahuila, Hidalgo, Nayarit, and Morelos), and USA (Texas and Arizona) (Fig. 8 ).

Habitat and ecology.

Edges of streams, lagoons, or lakes, in flooded and waterlogged areas. Frequently forming dense populations, however, it is usually found scattered or as isolated plants along riverbanks.

Phenology.

It flowers from March to July, and bears fruit in August to December. Flowers or fruits may be found throughout the year on isolated plants, especially in the southernmost populations.

Additional material examined.

EL SALVADOR - Morazán • Rio Sapo , area burnt ca 20 years prior; 13°55 ’47” N, 88°06 ’01” W; 678 m; 25 Mar. 2002; Monro 3808; MO .

HONDURAS - Choluteca • Common along Rio Pespire , vicinity of Pespire; 15 Mar. 1967; Molina 20620 ; US [ US 02370571]. - El Paraíso • Yuscarán, Aldea El Rodeo , quebrada Las Zarcas , road to Oropolí; 13°53 ’06” N, 86°46 ’47” W; 420 m; 3 May 2000; Molina R. et al. 34926; MO. • El Paraíso, common along river thickets, in pine forest area along fossil deposit of arenal river bed, 3 Kms East of Ojo de Agua ; 25 Feb. 1969; Molina 23361 ; US [ US 02370569]. - Francisco Morazan • Yaguasire, campo abierto; 10 May 1981; Midence 117 ; US [ US 02370570] • Lempira, Municipio San Miguelito , common along river, pine forest area El Comedero, road to Gracias; 4 Mar. 1969; Molina 24007 ; US [ US 02370567].

MEXICO - Colima • Ruta 110, Colima a Pihuamo , Km 215 a Rio Salado ; 19°11 ’32” N, 103°41 ’45” W; 300 m; 18 Jan. 1982; Lorence et al. 3798; MO . - Chihuahua • Allende, Valle de Allende, Balneario Ojo de Talamantes ; 26.90°19 ’93” N, 105.45°73 ’49” W; 5400 ft; 29 Aug. 1990; Swagel 272; MO . - Coahuila • Castaños, San Lázaro, near the northern entrance of El Puerto de San Lazaro ; 16 Jun. 1936; Wynd & Muller 118; MO . - Hidalgo • Jojutla ; 31 Aug. 1902; Pringle 9822; SI . - Nayarit • San Blas, 3.8 Km al SE de Tecuitata sobre camino a tierra El Cora , carr. Jalcocotan-Miramar ; 21°26 ’16” N, 105°08 ’13” W; 10 Nov. 1994; Flores F. & Téllez V. 3435; CTES, MEXU . - Morelos • Cuernavaca ; 16 Jan. 1901; Pringle 8474; SI .

USA - Arizona • Pima Co., Coronado National Forest T 16S, R18E, Sec. 1. Coronado National Forest along Forest Rd. 35, Ash Creek drainage; 32°04 ’36” N, 110°27'W; 1140 m; 12 Sep. 1998; Brant & Stone 3982; MO, UMO . - Texas • Starr Co., Santa Margarita Ranch, on W side of State Highway 83 via Santa Margarita Road , which branches from highway ca 9 miles N and W of Roma , Bank of Rio Grande ; 26°28 ’34” N, 99°05 ’29” W; 185 ft; 7 Oct. 2017; Yatskievych et al. 17-162; MO, TEX .

Figures

Figure 8. Distribution map of Cephalanthus occidentalis and C. salicifolius.

Figure 9. Cephalanthus salicifolius. A. Flowering branch. B. Stipule. C. Axils of the middle and secondary veins showing domatia as tufts of hairs. D. Partial inflorescence. E. Perfect flower. F. Flower with exerted style and stigma. G. Unfolded corolla. H. Style and stigma. I. Dorsal view of schizocarp. J. Lateral view of mericarp. K. Lateral view of seed with aril. L. Dorsal view of seed with aril. Drawn by Laura Simon.