Croton polygonoides Smith & Downs (1959: 151)

Pereira, Amanda Da Paixão Noronha, Riina, Ricarda & Caruzo, Maria Beatriz Rossi, 2022, Croton (Euphorbiaceae) of the Brazilian state of Paraná: an annotated checklist, species distribution, and identification key, Phytotaxa 570 (3), pp. 231-274 : 254-256

26. Croton polygonoides Smith & Downs (1959: 151) .

Type: — BRAZIL. Santa Catarina: Dionísio Cerqueira , 31 December 1956, L.B. Smith, P.R. Reitz & D. Pereira 9681 (holotype US 00109650 !; isotypes NY 00262939!, R 000200948!) (Illustration available in Smith et al. 1988: 100).

Croton polygonoides is a rare and poorly known species ( Smith et al. 1988), which can be recognized by its glabrescent to sparsely pubescent leaves with basilaminar nectary glands, and lax inflorescences. Smith & Downs (1956), in the protologue of the species, describe the presence of glands at the base of the bracts, however, these structures were not seen in the collections examined here. Croton polygonoides is morphologically similar to C. sanctae-crucis due to its discolorous leaves with raised veins, and sessile pistillate flowers. The two species differ mainly by the adaxial leaf surface (glabrous in C. polygonoides vs. sparsely pubescent in C. sanctae-crucis ), abaxial leaf surface (glabrescent sparsely pubescent in C. polygonoides vs. pubescent in C. sanctae-crucis ), leaf shape (elliptic in C. polygonoides vs. lanceolate to ovate in C. sanctae-crucis ), staminate flowers (pedicellate in C. polygonoides vs. sessile or subsessile in C. sanctae-crucis ), and habitat ( C. polygonoides occurs along the edges of Araucaria forest whereas C. sanctae-crucis occurs only in cerrado). C. polygonoides is a member to section Adenophylli subsect. Meridionalis ( van Ee & Berry 2021) .

Distribution and habitat:— It occurs in southern (PR, SC) Brazil ( Smith et al. 1988). Although it was reported by Caruzo et al. (2020) for Rio Grande do Sul, we were unable to find collections from this species from Rio Grande do Sul neither online nor in any of the visited herbaria. The few existing records indicate the species grow along the edges of Araucaria forest , in moist soil, apparently between 500 and 600 m elevation ( Fig. 14 ).

Phenology:— Flowering and fruiting from May and October.

Representative specimens:— PARANÁ: Santo Antônio do Sudoeste, Planchita , 24 October 1969, G . Hatschbach 22639 ( BR, K, MBM, MO, NY, UPCB). Idem , arredores, 17 May 1977, G . Hatschbach 39923 ( MBM) .

Figures

FIGURE 14. Map showing the known geographic distributions of Croton myrianthus, C. polygonoides, C. pycnocephalus, and C. reitzii in Paraná state.