Alexandre Alonso - Academia.edu (original) (raw)

Papers by Alexandre Alonso

Studies on the Orchidaceae family in the Chapada dos Veadeiros National Park revealed a new occur... more Studies on the Orchidaceae family in the Chapada dos Veadeiros National Park revealed a new occurrence for the family to the flora of the Goiás state. Bulbophyllum adiamantinum, hitherto considered endemic to the state of Minas Gerais, is described here, illustrated, commented on its distribution, morphological relationships and period of flowering and fruiting. In addition, a map with distribution this species, its preliminary conservation status, images and notes on the anatomy of its vegetative system and its more morphologically, B. insectiferum, with which it can be confused, are provided. Anatomically, both species differ mainly by the presence or absence of silica bodies in the vegetative system and tracheoid idioblasts in the mesophyll, by the arrangement of the fibers and the appearance of the lumen of the cells of the exoderm, endoderm, pericycle and medulla in the roots. The characters that showed themselves to be variables were the number of vascular bundles, the shape o...

Plant Systematics and Evolution, 2019

Chamaecrista oligandra from the Brazilian Cerrado, the most diverse savannah and one of 34 hot sp... more Chamaecrista oligandra from the Brazilian Cerrado, the most diverse savannah and one of 34 hot spots of the world, is herein described, illustrated, and compared with C. flexuosa var. flexuosa and C. parvistipula, its morphologically similar congeners. The flowering and fruiting, environmental preferences, distribution map, images, and preliminary conservation status of the new species are provided. Additionally, leaf anatomy and scanning electron microscopy of the leaf petiolar nectaries of the new species and the two putative closest relatives were compared. A phylogeny based on the noncoding plastidial (trnL-trnF) and nuclear ribosomal internal transcribed spacer indicated the proper placement of C. oligandra sp. nov. in Chamaecrista sect. Chamaecrista ser. Flexuosae, which is a taxonomic group that includes sub-shrubby species with underground systems conspicuously developed, leaflets with palmate-dimidiate venation, and flowers in an axillary fascicle. A key to identify species of the C. ser. Flexuosae series is provided to facilitate recognition of species that are distributed in open areas of the Brazilian Cerrado and frequently misidentified in collections.

Plant Systematics and Evolution, 2019

Croton macrosepalus Sodré & M.J.Silva (sp. nov.), a new species found in the states of Bahia, Goi... more Croton macrosepalus Sodré & M.J.Silva (sp. nov.), a new species found in the states of Bahia, Goiás, and Tocantins, in Brazil, is described and illustrated. Although it is morphologically similar to Croton spica, the novel species can be differentiated from it by having large glandular stipules, entire or sometimes serrulate leaf margins, petioles with 2-8 cylindrical nectary glands at the apex, ovate pistillate sepals, and a hat-shaped caruncle. The habitat, conservation status, phenology, and morphological relationships of the species are also discussed. Morphological data and molecular analyses using ITS and trnL-trnF support the placement of C. macrosepalus and C. spica in Croton sect. Geiseleria. A geographic distribution map, images, notes about the leaf anatomy of both species, and their phylogenetic relationships are provided.

Nordic Journal of Botany, 2016

Manihot allemii M. J. Silva is described and illustrated as a new species, and its morphological ... more Manihot allemii M. J. Silva is described and illustrated as a new species, and its morphological affinities and conservation status is discussed. It is most similar to M. salicifolia Pohl in having a subshrubby and erect habit and in the general aspect of its unlobed leaves, but differs from it in having leaves that are conspicuously petiolate, an inflorescence that is a congested spike-like thyrse, entire and diminute bracts and bracteoles subtending flowers of both sexes, pistillate calyx that is deeply lobed with oblong lobes, and staminate flowers with 8 or 10 stamens. Both species belong to a group of 14 species recognized by their possession of entire and unlobed leaves, which are the subject of taxonomic studies by the second author. Some notes on the leaf anatomy of species of Manihot that have entire and unlobed leaves are also presented.

During the preparation of the taxonomic treatment of Manihot in the Midwest Region of Brazil, a n... more During the preparation of the taxonomic treatment of Manihot in the Midwest Region of Brazil, a new species was found. Manihot fallax M.J. Silva & L.S. Inocencio is described, illustrated and morphologically compared with similar simple-leaved species. The conservation status, geographic distribution (including map), ecology, phenology and notes about leaf anatomy of the new species are given. The synonymisation of M. robusta M. Mend. & T. B. Cavalc. under M. attenuata Müll. Arg. and lectotypes for M. attenuata and M. brachystachys Pax & K. Hoffm are also proposed. An emended description of M. attenuata is proposed as the original description is incomplete as it lacks information on the pistillate flowers, fruits and seeds.

Phytotaxa, 2022

A new species from the state of Goiás, Brazil, Phyllanthus pterocaulis, is described and illustra... more A new species from the state of Goiás, Brazil, Phyllanthus pterocaulis, is described and illustrated, with comments on its geographic distribution and environmental preferences, phenology, morphological relationships, and systematic position. It is morphologically allied with Phyllanthus avicularis, P. heliotropus, and P. hyssopifolioides, but differs from all of them by a set of characters related to cymules sex, presence and types of trichomes on leaves and stems, leaf consistency, numbers of sepals in flower of both sexes, integrity of stamens, capsules and seeds. Additionally, we provide images of the new species in the field, conservation status, mapped distribution, the anatomical description of its stem and leaves, and a key to differentiate it from the other similar species belonging to Phyllanthus sect. Loxopodium occurring in Brazil. The new species is one of the few in the genus that occurs in shaded environments in seasonal dry forests within the Cerrado biome.

Journal of medicinal plant research

An infusion of 5% Byrsonima japurensis stem bark, an Amazonian medicinal plant, presented anti-in... more An infusion of 5% Byrsonima japurensis stem bark, an Amazonian medicinal plant, presented anti-inflammatory, anti-hyperalgesic, antiplatelet and antiulcer activity in a previous study. In this study, pharmacognostical parameters for this raw material were determined and the technological characterization of the infusion was performed, concurrently with the assessment of their antioxidant potential. The analysis of the raw material and the crude extract was done using pharmacopoeial and non-pharmacopeial methods. The antioxidant potential was evaluated by diphenylpicrylhydrazyl (DPPH•), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS•+) and nitric oxide (NO•) radical scavenger assays. The raw material presented a mean size of particles of 318.30 ± 1.65 µm, ash content of 3.39 ± 0.04 g%, 10.32 ± 0.09 g% loss on drying and 12.23 ± 0.17 g% of matter extractable by water. The extract obtained by infusion of 5% of plant drug is rich in polyphenol compounds (50.69 ± 3.64 mg GAE/g) with appreciable flavonoid content (2.38 ± 1.15 mg quercetin/g). This extract showed expressive antioxidant activity, which was significantly better than ascorbic acid and Trolox in both DPPH and ABTS radical scavengers tests (p < 0.05), which is closely related to its previously detected anti-inflammatory activity

Brittonia

Chamaecrista belladonna is described and illustrated. It is assigned to Chamaecrista sect. Absus ... more Chamaecrista belladonna is described and illustrated. It is assigned to Chamaecrista sect. Absus subsect. Absus series Microphyllae. The species grows on mixed sand-clay soils near rock outcrops in the Chapada dos Veadeiros region in the Brazilian state of Goiás. Since it is found in an area 0.4 km2, surrounded by agricultural land and under intense anthropogenic pressure, it is here considered Critically Endangered. The novel species can be distinguished from all other species of the series by having pseudo-terminal inflorescences (borne in the axil of the distal-most leaf at the ends of branches and appearing opposite the leaf) with flexuous axis and leaflets with mixed acrodromous-brochidodromous venation. Discussion is provided about the distribution, phenology, and conservation status of the new species, as well as its morphological relationships with the similar species C. dumalis and C. imbricans. Images and descriptions of the leaf anatomy of the new species are also given.

Rodriguésia

Resumo Estudos sobre a família Orchidaceae no Parque Nacional da Chapada dos Veadeiros, revelou u... more Resumo Estudos sobre a família Orchidaceae no Parque Nacional da Chapada dos Veadeiros, revelou uma nova ocorrência para a flora do estado de Goiás. Bulbophyllum adiamantinum até então considerada endêmica do estado de Minas Gerais, é aqui descrita, ilustrada, comentada quanto a sua distribuição, relações morfológicas e épocas de floração e frutificação. Adicionalmente, são fornecidos um mapa com a distribuição da espécie, seu status de conservação, além de imagens e notas sobre a anatomia de seu sistema vegetativo e de B. insectiferum, com a qual pode ser confundida. Anatomicamente, ambas as espécies se diferenciam principalmente pela presença ou ausência de corpos silicosos no sistema vegetativo, de idioblastos traqueoidais no mesofilo, pelo arranjo das fibras e aspecto do lume nas células da exoderme, endoderme, periciclo e medula nas raízes. Os caracteres que mostraram-se variáveis foram o número de feixes vasculares, o formato das células da epiderme e a espessura da cutícula d...

PhytoKeys, 2017

During the preparation of the taxonomic treatment of Manihot in the Midwest Region of Brazil, a n... more During the preparation of the taxonomic treatment of Manihot in the Midwest Region of Brazil, a new species was found. Manihot fallax M.J. Silva & L.S. Inocencio is described, illustrated and morphologically compared with similar simple-leaved species. The conservation status, geographic distribution (including map), ecology, phenology and notes about leaf anatomy of the new species are given. The synonymisation of M. robusta M. Mend. & T. B. Cavalc. under M. attenuata Müll. Arg. and lectotypes for M. attenuata and M. brachystachys Pax & K. Hoffm are also proposed. An emended description of M. attenuata is proposed as the original description is incomplete as it lacks information on the pistillate flowers, fruits and seeds.

Phytotaxa, 2015

Chamaecrista irwiniana, a new species of Chamaecrista sect. Absus subsect. Absus ser. Rigidulae, ... more Chamaecrista irwiniana, a new species of Chamaecrista sect. Absus subsect. Absus ser. Rigidulae, is here described and illustrated. Its morphological affinities, geographical distribution, ecology, conservation status, and information about leaf anatomy are also presented. Additionally, a complete description, distribution, and the first illustration of C. nummulariifolia, an endemic species to the states of Goiás and Minas Gerais, classified as vulnerable according to the IUCN guidelines, are provided.

Comunicata Scientiae, 2013

In this paper described the anatomical distribution of laticifers from the bark of Hura crepitans... more In this paper described the anatomical distribution of laticifers from the bark of Hura crepitans and Ficus maxima, typical floodplain trees in the Amazon forest. By observing samples which were processed by usual plant anatomy techniques, it was possible to verify that there were laticifers presenting radial distribution in the secondary stem phloem of F. maxima, and a diffuse distribution in the axial phloem in H. crepitans.

Acta Bot Bras, 2004

RESUMO -(Endoderme com atividade meristemática em raiz de Canna edulis Kerr-Gawler (Cannaceae)). ... more RESUMO -(Endoderme com atividade meristemática em raiz de Canna edulis Kerr-Gawler (Cannaceae)). Canna edulis é uma planta ornamental utilizada em muitos países como fonte alimentar alternativa. O objetivo deste trabalho foi descrever a formação do córtex radicular a partir da análise anatômica da região apical. Na região situada a 220µm do pró-meristema, os tecidos meristemáticos apicais já se apresentam organizados em protoderme, meristema fundamental e procâmbio. Em fase subseqüente na diferenciação celular, a 450µm do pró-meristema, as camadas de células do córtex estão dispostas em fileiras radiais iniciando-se na endoderme. Depois que as iniciais endodérmicas cessam as divisões, adquirem estrias de Caspary. Na raiz, a 1.700µm do pró-meristema, os tecidos primários já se encontram diferenciados, sendo o padrão de distribuição celular observado no córtex de C. edulis característico ao apresentado por outras espécies de Zingiberales. A análise anatômica da região apical levou à constatação que 2/3 do córtex é resultante da atividade meristemática da endoderme e o restante das células corticais são originadas diretamente do meristema fundamental.

Nordic Journal of Botany, 2016

Comunicata Scientiae, Jul 1, 2013

In this paper described the anatomical distribution of laticifers from the bark of Hura crepitans... more In this paper described the anatomical distribution of laticifers from the bark of Hura crepitans and Ficus maxima, typical floodplain trees in the Amazon forest. By observing samples which were processed by usual plant anatomy techniques, it was possible to verify that there were laticifers presenting radial distribution in the secondary stem phloem of F. maxima, and a diffuse distribution in the axial phloem in H. crepitans.

Studies on the Orchidaceae family in the Chapada dos Veadeiros National Park revealed a new occur... more Studies on the Orchidaceae family in the Chapada dos Veadeiros National Park revealed a new occurrence for the family to the flora of the Goiás state. Bulbophyllum adiamantinum, hitherto considered endemic to the state of Minas Gerais, is described here, illustrated, commented on its distribution, morphological relationships and period of flowering and fruiting. In addition, a map with distribution this species, its preliminary conservation status, images and notes on the anatomy of its vegetative system and its more morphologically, B. insectiferum, with which it can be confused, are provided. Anatomically, both species differ mainly by the presence or absence of silica bodies in the vegetative system and tracheoid idioblasts in the mesophyll, by the arrangement of the fibers and the appearance of the lumen of the cells of the exoderm, endoderm, pericycle and medulla in the roots. The characters that showed themselves to be variables were the number of vascular bundles, the shape o...

Plant Systematics and Evolution, 2019

Chamaecrista oligandra from the Brazilian Cerrado, the most diverse savannah and one of 34 hot sp... more Chamaecrista oligandra from the Brazilian Cerrado, the most diverse savannah and one of 34 hot spots of the world, is herein described, illustrated, and compared with C. flexuosa var. flexuosa and C. parvistipula, its morphologically similar congeners. The flowering and fruiting, environmental preferences, distribution map, images, and preliminary conservation status of the new species are provided. Additionally, leaf anatomy and scanning electron microscopy of the leaf petiolar nectaries of the new species and the two putative closest relatives were compared. A phylogeny based on the noncoding plastidial (trnL-trnF) and nuclear ribosomal internal transcribed spacer indicated the proper placement of C. oligandra sp. nov. in Chamaecrista sect. Chamaecrista ser. Flexuosae, which is a taxonomic group that includes sub-shrubby species with underground systems conspicuously developed, leaflets with palmate-dimidiate venation, and flowers in an axillary fascicle. A key to identify species of the C. ser. Flexuosae series is provided to facilitate recognition of species that are distributed in open areas of the Brazilian Cerrado and frequently misidentified in collections.

Plant Systematics and Evolution, 2019

Croton macrosepalus Sodré & M.J.Silva (sp. nov.), a new species found in the states of Bahia, Goi... more Croton macrosepalus Sodré & M.J.Silva (sp. nov.), a new species found in the states of Bahia, Goiás, and Tocantins, in Brazil, is described and illustrated. Although it is morphologically similar to Croton spica, the novel species can be differentiated from it by having large glandular stipules, entire or sometimes serrulate leaf margins, petioles with 2-8 cylindrical nectary glands at the apex, ovate pistillate sepals, and a hat-shaped caruncle. The habitat, conservation status, phenology, and morphological relationships of the species are also discussed. Morphological data and molecular analyses using ITS and trnL-trnF support the placement of C. macrosepalus and C. spica in Croton sect. Geiseleria. A geographic distribution map, images, notes about the leaf anatomy of both species, and their phylogenetic relationships are provided.

Nordic Journal of Botany, 2016

Manihot allemii M. J. Silva is described and illustrated as a new species, and its morphological ... more Manihot allemii M. J. Silva is described and illustrated as a new species, and its morphological affinities and conservation status is discussed. It is most similar to M. salicifolia Pohl in having a subshrubby and erect habit and in the general aspect of its unlobed leaves, but differs from it in having leaves that are conspicuously petiolate, an inflorescence that is a congested spike-like thyrse, entire and diminute bracts and bracteoles subtending flowers of both sexes, pistillate calyx that is deeply lobed with oblong lobes, and staminate flowers with 8 or 10 stamens. Both species belong to a group of 14 species recognized by their possession of entire and unlobed leaves, which are the subject of taxonomic studies by the second author. Some notes on the leaf anatomy of species of Manihot that have entire and unlobed leaves are also presented.

During the preparation of the taxonomic treatment of Manihot in the Midwest Region of Brazil, a n... more During the preparation of the taxonomic treatment of Manihot in the Midwest Region of Brazil, a new species was found. Manihot fallax M.J. Silva & L.S. Inocencio is described, illustrated and morphologically compared with similar simple-leaved species. The conservation status, geographic distribution (including map), ecology, phenology and notes about leaf anatomy of the new species are given. The synonymisation of M. robusta M. Mend. & T. B. Cavalc. under M. attenuata Müll. Arg. and lectotypes for M. attenuata and M. brachystachys Pax & K. Hoffm are also proposed. An emended description of M. attenuata is proposed as the original description is incomplete as it lacks information on the pistillate flowers, fruits and seeds.

Phytotaxa, 2022

A new species from the state of Goiás, Brazil, Phyllanthus pterocaulis, is described and illustra... more A new species from the state of Goiás, Brazil, Phyllanthus pterocaulis, is described and illustrated, with comments on its geographic distribution and environmental preferences, phenology, morphological relationships, and systematic position. It is morphologically allied with Phyllanthus avicularis, P. heliotropus, and P. hyssopifolioides, but differs from all of them by a set of characters related to cymules sex, presence and types of trichomes on leaves and stems, leaf consistency, numbers of sepals in flower of both sexes, integrity of stamens, capsules and seeds. Additionally, we provide images of the new species in the field, conservation status, mapped distribution, the anatomical description of its stem and leaves, and a key to differentiate it from the other similar species belonging to Phyllanthus sect. Loxopodium occurring in Brazil. The new species is one of the few in the genus that occurs in shaded environments in seasonal dry forests within the Cerrado biome.

Journal of medicinal plant research

An infusion of 5% Byrsonima japurensis stem bark, an Amazonian medicinal plant, presented anti-in... more An infusion of 5% Byrsonima japurensis stem bark, an Amazonian medicinal plant, presented anti-inflammatory, anti-hyperalgesic, antiplatelet and antiulcer activity in a previous study. In this study, pharmacognostical parameters for this raw material were determined and the technological characterization of the infusion was performed, concurrently with the assessment of their antioxidant potential. The analysis of the raw material and the crude extract was done using pharmacopoeial and non-pharmacopeial methods. The antioxidant potential was evaluated by diphenylpicrylhydrazyl (DPPH•), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS•+) and nitric oxide (NO•) radical scavenger assays. The raw material presented a mean size of particles of 318.30 ± 1.65 µm, ash content of 3.39 ± 0.04 g%, 10.32 ± 0.09 g% loss on drying and 12.23 ± 0.17 g% of matter extractable by water. The extract obtained by infusion of 5% of plant drug is rich in polyphenol compounds (50.69 ± 3.64 mg GAE/g) with appreciable flavonoid content (2.38 ± 1.15 mg quercetin/g). This extract showed expressive antioxidant activity, which was significantly better than ascorbic acid and Trolox in both DPPH and ABTS radical scavengers tests (p < 0.05), which is closely related to its previously detected anti-inflammatory activity

Brittonia

Chamaecrista belladonna is described and illustrated. It is assigned to Chamaecrista sect. Absus ... more Chamaecrista belladonna is described and illustrated. It is assigned to Chamaecrista sect. Absus subsect. Absus series Microphyllae. The species grows on mixed sand-clay soils near rock outcrops in the Chapada dos Veadeiros region in the Brazilian state of Goiás. Since it is found in an area 0.4 km2, surrounded by agricultural land and under intense anthropogenic pressure, it is here considered Critically Endangered. The novel species can be distinguished from all other species of the series by having pseudo-terminal inflorescences (borne in the axil of the distal-most leaf at the ends of branches and appearing opposite the leaf) with flexuous axis and leaflets with mixed acrodromous-brochidodromous venation. Discussion is provided about the distribution, phenology, and conservation status of the new species, as well as its morphological relationships with the similar species C. dumalis and C. imbricans. Images and descriptions of the leaf anatomy of the new species are also given.

Rodriguésia

Resumo Estudos sobre a família Orchidaceae no Parque Nacional da Chapada dos Veadeiros, revelou u... more Resumo Estudos sobre a família Orchidaceae no Parque Nacional da Chapada dos Veadeiros, revelou uma nova ocorrência para a flora do estado de Goiás. Bulbophyllum adiamantinum até então considerada endêmica do estado de Minas Gerais, é aqui descrita, ilustrada, comentada quanto a sua distribuição, relações morfológicas e épocas de floração e frutificação. Adicionalmente, são fornecidos um mapa com a distribuição da espécie, seu status de conservação, além de imagens e notas sobre a anatomia de seu sistema vegetativo e de B. insectiferum, com a qual pode ser confundida. Anatomicamente, ambas as espécies se diferenciam principalmente pela presença ou ausência de corpos silicosos no sistema vegetativo, de idioblastos traqueoidais no mesofilo, pelo arranjo das fibras e aspecto do lume nas células da exoderme, endoderme, periciclo e medula nas raízes. Os caracteres que mostraram-se variáveis foram o número de feixes vasculares, o formato das células da epiderme e a espessura da cutícula d...

PhytoKeys, 2017

During the preparation of the taxonomic treatment of Manihot in the Midwest Region of Brazil, a n... more During the preparation of the taxonomic treatment of Manihot in the Midwest Region of Brazil, a new species was found. Manihot fallax M.J. Silva & L.S. Inocencio is described, illustrated and morphologically compared with similar simple-leaved species. The conservation status, geographic distribution (including map), ecology, phenology and notes about leaf anatomy of the new species are given. The synonymisation of M. robusta M. Mend. & T. B. Cavalc. under M. attenuata Müll. Arg. and lectotypes for M. attenuata and M. brachystachys Pax & K. Hoffm are also proposed. An emended description of M. attenuata is proposed as the original description is incomplete as it lacks information on the pistillate flowers, fruits and seeds.

Phytotaxa, 2015

Chamaecrista irwiniana, a new species of Chamaecrista sect. Absus subsect. Absus ser. Rigidulae, ... more Chamaecrista irwiniana, a new species of Chamaecrista sect. Absus subsect. Absus ser. Rigidulae, is here described and illustrated. Its morphological affinities, geographical distribution, ecology, conservation status, and information about leaf anatomy are also presented. Additionally, a complete description, distribution, and the first illustration of C. nummulariifolia, an endemic species to the states of Goiás and Minas Gerais, classified as vulnerable according to the IUCN guidelines, are provided.

Comunicata Scientiae, 2013

In this paper described the anatomical distribution of laticifers from the bark of Hura crepitans... more In this paper described the anatomical distribution of laticifers from the bark of Hura crepitans and Ficus maxima, typical floodplain trees in the Amazon forest. By observing samples which were processed by usual plant anatomy techniques, it was possible to verify that there were laticifers presenting radial distribution in the secondary stem phloem of F. maxima, and a diffuse distribution in the axial phloem in H. crepitans.

Acta Bot Bras, 2004

RESUMO -(Endoderme com atividade meristemática em raiz de Canna edulis Kerr-Gawler (Cannaceae)). ... more RESUMO -(Endoderme com atividade meristemática em raiz de Canna edulis Kerr-Gawler (Cannaceae)). Canna edulis é uma planta ornamental utilizada em muitos países como fonte alimentar alternativa. O objetivo deste trabalho foi descrever a formação do córtex radicular a partir da análise anatômica da região apical. Na região situada a 220µm do pró-meristema, os tecidos meristemáticos apicais já se apresentam organizados em protoderme, meristema fundamental e procâmbio. Em fase subseqüente na diferenciação celular, a 450µm do pró-meristema, as camadas de células do córtex estão dispostas em fileiras radiais iniciando-se na endoderme. Depois que as iniciais endodérmicas cessam as divisões, adquirem estrias de Caspary. Na raiz, a 1.700µm do pró-meristema, os tecidos primários já se encontram diferenciados, sendo o padrão de distribuição celular observado no córtex de C. edulis característico ao apresentado por outras espécies de Zingiberales. A análise anatômica da região apical levou à constatação que 2/3 do córtex é resultante da atividade meristemática da endoderme e o restante das células corticais são originadas diretamente do meristema fundamental.

Nordic Journal of Botany, 2016

Comunicata Scientiae, Jul 1, 2013

In this paper described the anatomical distribution of laticifers from the bark of Hura crepitans... more In this paper described the anatomical distribution of laticifers from the bark of Hura crepitans and Ficus maxima, typical floodplain trees in the Amazon forest. By observing samples which were processed by usual plant anatomy techniques, it was possible to verify that there were laticifers presenting radial distribution in the secondary stem phloem of F. maxima, and a diffuse distribution in the axial phloem in H. crepitans.