Rumex subgen. Rumex sect. Axillares (Polygonaceae) in South America

• Published in: Plant systematics and evolution 1990-01, Vol.172 (1/4), p.151-192
• Main Author: Rechinger, K.H
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biological taxonomies; Endemic species; Fruiting; Fundamental and applied biological sciences. Psychology; Genetic hybridization; geographical distribution; Hybridity; hybridization; Inflorescences; keys; Leaves; new species; new taxa; Panicles; Pedicels; Plant cytology, morphology, systematics, chorology and evolution; Rumex; rumex hasslerianus; rumex selowianus; rumex uruguayensis; rumuex polyklonos; Spermatophyta; Stems; Systematics (diagnosis, chromosome numbers); taxonomy
• ISSN: 0378-2697; 1615-6110
• DOI: 10.1007/BF00937805

Rumex sect. Axillares first described by the author in 1937 is known to be represented in N. America by 20 endemic species. From S. America only five species, all endemic, were previously known; this number is raised in the present revision to 15. Outside America there exist small groups of endemic species in S. Africa and in the islands of Hawaii as well as in Australia and scattered single species in C. Africa, on the remote Atlantic islands of Tristan de Cunha and Gough Island, and in eastern Asia. — In Europe the section is completely absent, except for three American species which occur as rare aliens. The Axillares are not only morphologically well-characterized by their growth — no leaf rosettes, flowering period practically unlimited by formation of later flowering axillary shoots, flowers often monoecious — but also by their genetic structure expressed by a different behaviour in hybridization. Hybrids are frequent between species of sect. Rumex (syn. Simplices) and are easy to recognize by their sterility which results in a certain peculiarity in habit. In contrast, no spontaneous hybrids are known with certainty among species of sect. Axillares. Most artificial hybrids are fairly fertile. So far only three hybrids between species of the two sections have been known. Three more have been found by the author in Chile, all being highly sterile and showing the growth characteristics resulting from sterility as occur in hybrids between species of sect. Rumex. Rumex sección Axillares fue descrito por primera vez por el autor en 1937. Se conoce en América del Norte con 20 especies endémicas. De América del Sur se conocían sólo 5 especies, todas ellas endémicas; este número asciende a 15 en la presente revision. Fuera de las Américas se encuentran pequeños grupos de especies endémicas en Sudáfrica, en las Islas de Hawaii y en Australia; especies aisladas se encuentran en Africa Central, en las lejanas Islas Atlánticas de Tristan de Cunha y Gough Island y en Asia Oriental. La sección no tiene representantes en Europa, con excepción de tres especies americanas introducidas, poco frecuentes. La sección Axillares se caracteriza bien, tanto morfológi-camente por su forma de creciemiento — sin rosetas foliares, período floral prácticamente ilimitado por la formación de inflorescencias axilares parciales, flores a menudo monoicas — como por su estructura genética que se manifiesta en un comportamiento diferente de hibridación. Híbridos son frecuentes en las es