Are the trichomes in corollas of Mutisieae (Asteraceae) really twin hairs?

The corollas of three species of Onoseris, 13 species of Trichocline and one species of Uechtritzia (Asteraceae, Mutisieae) exhibit trichomes that are morphologically similar to the twin hairs which are traditionally considered exclusive of the cypselas in Asteraceae. Four types of trichomes were found: 1-celled, 2-celled, 3-celled, and 4-celled. The 3-celled and 4-celled corolla hairs are those which most resemble the typical cypsela twin hairs. The ontogeny of the corolla hairs was analysed and coincidences with the ontogeny of the cypsela twin hairs were found. (1) An anticlinal division of the epidermal mother cell originates two hair cells which, in turn, originate the basal cells (sometimes one of them is reduced or similar to the epidermal cells) by oblique or periclinal subdivision. (2) In some cases the basal cell(s) of the 3- or 4-celled corolla hair elongates and reaches the same length as the hair cells. The same kind of trichomes have been demonstrated in cypselas of Mutisieae. (3) The 1- and 2-celled corolla hairs have already been described as variants of the cypsela twin hairs. Based on this evidence we conclude that the corolla hairs of Onoseris, Trichocline and Uechtritzia are twin hairs. It is hypothesized that the 1-4 corolla hairs could be involved in water absorption, as occurs in the cypsela twin hairs.Facultad de Ciencias Naturales y Muse

Are the trichomes in corollas of Mutisieae (Asteraceae) really twin hairs?

The corollas of three species of Onoseris, 13 species of Trichocline and one species of Uechtritzia (Asteraceae, Mutisieae) exhibit trichomes that are morphologically similar to the twin hairs which are traditionally considered exclusive of the cypselas in Asteraceae. Four types of trichomes were found: 1-celled, 2-celled, 3-celled, and 4-celled. The 3-celled and 4-celled corolla hairs are those which most resemble the typical cypsela twin hairs. The ontogeny of the corolla hairs was analysed and coincidences with the ontogeny of the cypsela twin hairs were found. (1) An anticlinal division of the epidermal mother cell originates two hair cells which, in turn, originate the basal cells (sometimes one of them is reduced or similar to the epidermal cells) by oblique or periclinal subdivision. (2) In some cases the basal cell(s) of the 3- or 4-celled corolla hair elongates and reaches the same length as the hair cells. The same kind of trichomes have been demonstrated in cypselas of Mutisieae. (3) The 1- and 2-celled corolla hairs have already been described as variants of the cypsela twin hairs. Based on this evidence we conclude that the corolla hairs of Onoseris, Trichocline and Uechtritzia are twin hairs. It is hypothesized that the 1-4 corolla hairs could be involved in water absorption, as occurs in the cypsela twin hairs.Facultad de Ciencias Naturales y Muse

Systematics of <i>Podocoma</i> (Asteraceae: Astereae): a generic reassessment

Podocoma is a southern South American genus of perennial herbs with short-radiate capitula with two- to four-seriate ray florets and a two- to three-seriate pappus of scabridulous setae. The ray florets have corollas with narrow limbs. The rostrate cypsela of Podocoma is one of the most distinct features of the genus. Podocoma, with many of the endemic southern South American genera of Astereae, is included in subtribe Podocominae. Podocoma traditionally contained seven mainly Brazilian species (P. asperrima, P. bellidifolia, P. blanchetiana, P. hieracifolia, P. hirsuta, P. regnellii and. P. spegazzinii), and its expansion to include two species of Conyza (C. notobellidiastrum and C. rivularis) was, perhaps, the most significant recent change in the generic concept of Podocoma. However, recent molecular- and morphology-based phylogenetic analyses do not support the inclusion of these two species in Podocoma. Morphological and anatomical studies were carried out in order to clarify the taxonomy of Podocoma and to delimit the genus and its species. On the basis of the results of these morphological and anatomical studies, and those from molecular- and morphology-based phylogenetic analyses, P. notobellidiastrum and P. rivularis are excluded from Podocoma and transferred to a new genus that is currently under description. Moreover, P. regnellii and P. asperrima are placed in synonymy with P. hirsuta and P. spegazzinii, respectively. Three species, P. bellidifolia, P. blanchetiana and P. hieracifolia, are recognized here as a complex of closely related species from a morphological point of view; however, they are treated separately.Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plat

Systematics of <i>Podocoma</i> (Asteraceae: Astereae): a generic reassessment

Podocoma is a southern South American genus of perennial herbs with short-radiate capitula with two- to four-seriate ray florets and a two- to three-seriate pappus of scabridulous setae. The ray florets have corollas with narrow limbs. The rostrate cypsela of Podocoma is one of the most distinct features of the genus. Podocoma, with many of the endemic southern South American genera of Astereae, is included in subtribe Podocominae. Podocoma traditionally contained seven mainly Brazilian species (P. asperrima, P. bellidifolia, P. blanchetiana, P. hieracifolia, P. hirsuta, P. regnellii and. P. spegazzinii), and its expansion to include two species of Conyza (C. notobellidiastrum and C. rivularis) was, perhaps, the most significant recent change in the generic concept of Podocoma. However, recent molecular- and morphology-based phylogenetic analyses do not support the inclusion of these two species in Podocoma. Morphological and anatomical studies were carried out in order to clarify the taxonomy of Podocoma and to delimit the genus and its species. On the basis of the results of these morphological and anatomical studies, and those from molecular- and morphology-based phylogenetic analyses, P. notobellidiastrum and P. rivularis are excluded from Podocoma and transferred to a new genus that is currently under description. Moreover, P. regnellii and P. asperrima are placed in synonymy with P. hirsuta and P. spegazzinii, respectively. Three species, P. bellidifolia, P. blanchetiana and P. hieracifolia, are recognized here as a complex of closely related species from a morphological point of view; however, they are treated separately.Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plat

Typification of names in Kaunia (Asteraceae, Eupatorieae, Oxylobinae)

During the revision of Kaunia (in prep.), we detected names which required typification or whose current typification was incorrect. After the analysis of protologues and original material, we designated six lectotypes and one neotype for seven names currently assigned to Kaunia, and we superseded one lectotype. We discuss the details for each case.Fil: Viera Barreto, Jessica Noelia. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sancho, Gisela. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

A revision of Lophopappus (Asteraceae, Nassauvieae)

Lophopappus (Asteraceae, Nassauvieae) comprises five species endemic to South America. The genus is defined by its shrubby habit with unarmed branches, actinodromous or acrodromous leaf venation, solitary or few capitula at the apex of the branches with bilabiate and/or tubular-funnelform corollas, dorsally papillose style branches, and apically plumose pappus bristles. Leaf anatomy, cypsela trichomes, and pappus morphology are examined here for the first time in this genus. Lophopappus cuneatus is corroborated as a distinct species, L. berberidifolius is established as a synonym of L. tarapacanus, and a lectotype is designated for L. foliosus. A comprehensive key to the species and detailed descriptions, geographical distribution, phenology, illustrations and distribution maps are provided for all taxa.Lophopappus (Asteraceae, Nassauvieae) comprende cinco especies endémicas de América del Sur. El género se define por su hábito arbustivo con ramas inermes, venación foliar actinódroma o acródroma, capítulos solitarios o en corto número en el ápice de las ramas, con corolas bilabiadas y/o tubulosas, ramas del estilo papilosas en el dorso y pajitas del papus plumosas en el ápice. Se examinan por primera vez en el género la anatomía foliar, tricomas del fruto y morfología del papus. Se corrobora que L. cuneatus es una especie independiente; L. berberidifolius es un sinónimo de L. tarapacanus; y se designa un lectotipo para L. foliosus. Se provee una clave de especies y descripciones detalladas, distribución geográfica, fenología, ilustraciones y mapas de distribución para cada especie.Fil: Katinas, Liliana. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sancho, Gisela. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vitali, Maira Soledad. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Are the trichomes in corollas of Mutisieae (Asteraceae) really twin hairs?

The corollas of three species of Onoseris, 13 species of Trichocline and one species of Uechtritzia (Asteraceae, Mutisieae) exhibit trichomes that are morphologically similar to the twin hairs which are traditionally considered exclusive of the cypselas in Asteraceae. Four types of trichomes were found: 1-celled, 2-celled, 3-celled, and 4-celled. The 3-celled and 4-celled corolla hairs are those which most resemble the typical cypsela twin hairs. The ontogeny of the corolla hairs was analysed and coincidences with the ontogeny of the cypsela twin hairs were found. (1) An anticlinal division of the epidermal mother cell originates two hair cells which, in turn, originate the basal cells (sometimes one of them is reduced or similar to the epidermal cells) by oblique or periclinal subdivision. (2) In some cases the basal cell(s) of the 3- or 4-celled corolla hair elongates and reaches the same length as the hair cells. The same kind of trichomes have been demonstrated in cypselas of Mutisieae. (3) The 1- and 2-celled corolla hairs have already been described as variants of the cypsela twin hairs. Based on this evidence we conclude that the corolla hairs of Onoseris, Trichocline and Uechtritzia are twin hairs. It is hypothesized that the 1-4 corolla hairs could be involved in water absorption, as occurs in the cypsela twin hairs.Facultad de Ciencias Naturales y Muse

Lectotypifications in Ophryosporus (Asteraceae, Eupatorieae, Critoniinae)

Se tipifican 10 nombres pertenecientes a especies de Ophryosporus, como una contribución nomenclatural a una próxima revisión taxonómica del género.Lectotypifications in Ophryosporus (Asteraceae, Eupatorieae, Critoniinae). Typification is provided for 10 names of Ophryosporus as a nomenclatural contribution to a forthcoming taxonomic revision of the genus.Facultad de Ciencias Naturales y Muse

Sobre la presencia de la División Plantas Vasculares del Museo de La Plata en nuestras tierras australes

Fil: Sancho, Gisela. División Plantas Vasculares. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Iharlegui, Laura. División Plantas Vasculares. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

On the presence of uncommon stylar glandular trichomes in Asteraceae: A study in <i>Kaunia</i> R. M. King and H. Rob. (Oxylobinae, Eupatorieae)

Premise of research. Glands on the styles of Asteraceae are uncommon. They are reported in Kaunia for the first time. Glandular trichomes of plants are involved in the synthesis of secondary metabolites. In Kaunia, secondary compounds with medicinal cytotoxic, antitumor activity, and sensitizing capacity were previously identified. In this frame, a deeper knowledge of glandular trichomes could shed light on the productivity of medicinal substances in Kaunia. The potential taxonomic and ecological value of stylar glandular trichomes in Kaunia is also explored together with trichome secretion phases throughout the floral developmental stages. Methodology. Herbarium specimens and flowers fixed in FAA of 10 species of Kaunia were analyzed. Flowers in different developmental stages were studied to observe the secretory phases of stylar trichomes. A histochemical test was carried out to detect sesquiterpene lactones on stylar glandular trichomes. Pivotal results. Glandular trichomes were detected on the ventral face of style branches in eight species of Kaunia in all floral stages analyzed. The stylar trichomes observed were mostly found in secretory or early postsecretory phases in the most immature floral stages. The histochemical test in stylar trichomes was positive for sesquiterpene lactones. Conclusions. The presence of stylar glandular trichomes provides valuable new evidence for the identification and characterization of Kaunia. Within the Eupatorieae, the presence of stylar glandular trichomes could be interpreted as taxonomically valuable at the rank of genus. Our finding of sesquiterpene lactones is in agreement with the presence of Guaianolides and Germacranolides previously isolated in Kaunia. Apparently, the secretion of trichomes is completed before the opening of the corolla. The glands on styles of Kaunia could be the most internal barrier to herbivores that could flank outer floral structures during pollen and style development.Facultad de Ciencias Naturales y Muse