Inflorescence evolution in Santalales: integrating morphological characters and molecular phylogenetics.

PREMISE OF THE STUDY: The sandalwood order (Santalales) includes members that present a diverse array of inflorescence types, some of which are unique among angiosperms. This diversity presents not only interpretational challenges but also opportunities to test fundamental concepts in plant morphology. Here we used modern phylogenetic approaches to address the evolution of inflorescences in the sandalwood order. METHODS: Phylogenetic analyses of two nuclear and three chloroplast genes were conducted on representatives of 146 of the 163 genera in the order. A matrix was constructed that scored nine characters dealing with inflorescences. One character, "trios", that encompasses any grouping of three flowers (i.e., both dichasia and triads) was optimized on samples of the posterior distribution of trees from the Bayesian analysis using BayesTraits. Three nodes were examined: the most recent common ancestors of (A) all ingroup members, (B) Loranthaceae, and (C) Opiliaceae, Santalaceae s.l., and Viscaceae. KEY RESULTS: The phylogenetic analysis resulted in many fully resolved nodes across Santalales with strong support for 18 clades previously named as families. The trios character was not supported for nodes A and C, whereas it was supported for node B where this partial inflorescence type is best described as a triad. CONCLUSIONS: Essentially every major inflorescence type can be found in Santalales; however, the dichasium, a type of partial inflorescence, is rarely seen and is not plesiomorphic for the order. In the family Erythropalaceae, inflorescences are mostly in small, axillary fascicles or cymes. Successive families show both cymose and racemose types and compound systems (e.g., thyrses). Inflorescences in Amphorogynaceae and Viscaceae are not dichasial and in general are difficult to compare to "standard" inflorescences.

Comparative inflorescence development in selected Andean Santalales.

PREMISE OF THE STUDY: Loranthaceae, Santalaceae, and Viscaceae are the most diversified hemiparasitic families of Santalales in the Andes. Their partial inflorescences (PIs) vary from solitary flowers, or dichasia in most Santalales, to congested floral groups along articles in most Viscaceae. The atypical articled inflorescences in Phoradendreae (Viscaceae), a phylogenetic novelty restricted to this tribe, have been variously described as racemes, spikes, fascicles, or as intercalary inflorescences, but no developmental studies have been performed to compare them with the construction of PIs across Santalales. METHODS: We used standard light microscopy and scanning electron microscopy to record the inflorescence development in members of Phoradendreae (Viscaceae) in comparison to those in species of Aetanthus, Gaiadendron, Oryctanthus, Passovia, and Peristethium (Loranthaceae) and Antidaphne (Santalaceae). KEY RESULTS: Morphological and developmental comparisons as well as optimization onto a phylogenetic framework indicate that individual inflorescences in Santalales are indeterminate and are formed by axillary cymose PIs. The latter correspond to dichasia, either simple, compound, or variously reduced by abortion of lateral flowers, abortion of the terminal flower, or loss of bracteoles. CONCLUSIONS: Dichasia are plesiomorphic in Santalales. These results favor the interpretation that inflorescences in Phoradendreae are formed by the fusion of serial dichasia (=floral rows) with the main inflorescence axis via syndesmy. We compared this interpretation with the competing one based on the co-occurrence of collateral and serial floral buds.

Morfoanatomia foliar de phoradendron obtusissimum(miq ) eichler (viscaceae), "ka'a votyre'y", utilizado con fines medicinales en una comunidad de Colonia Independencia, Paraguay / Leaf morphoanatomy of Phoradendron obtusissimum(Miq) Eichler (V iscaceae), "ka'avotyre'y", used for medicinal purposes in a community of Colonia Independencia, Paraguay

Resumen: El "ka'avotyre'y", Phoradendron obtusissimum (V iscaceae), es una especie empleada con fines medicinales en Paraguay para tratar enfermedades hepáticas. El presente trabajo se desarrolló dentro del marco del proyecto "Conservación, fortalecimiento y uso sostenible de la flora de Itá Azul y San Gervasio, Colonia Independencia, Reserva de Recursos Manejados Ybytyruzu, Paraguay" y tuvo por objetivo describir la morfoanatomía de P . obtusissimum. Los caracteres diferenciales son: estomas paracíticos en ambas epidermis, índice estomático en epidermis adaxial (5,71)-6,62-(8,33) y en epidermis abaxial (6,45)-1 1,20-(14,29); presencia de drusas en todo el mesófilo. Se presentan así elementos de diagnóstico útiles a la hora de identificar a la especie estudiada. Palabras clave: Phoradendron obtusissimum, morfoanatomía, planta medicinal.