Carpology of Some East Asian Cardueae (Asteraceae)
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Anales del Jardín Botánico de Madrid Vol. 65(1): 129-134 enero-junio 2008 ISSN: 0211-1322 Carpology of some East Asian Cardueae (Asteraceae) by E.V. Zarembo & E.V. Boyko Laboratory of plant chemotaxonomy, Pacific Institute of Bioorganic Chemistry, Far-East Division, Russian Academy of Sciences 690022, 100-letiya Vladivostoky Ave., 159, Vladivostok, Russia. [email protected] Abstract Resumen Zarembo, E.V. & Boyko, E.V. 2008. Carpology of some East Zarembo, E.V. & Boyko, E.V. 2008. Carpología de algunas Car- Asian Cardueae (Asteraceae). Anales Jard. Bot. Madrid 65(1): dueae (Asteraceae) de Asia oriental. Anales Jard. Bot. Madrid 129-134. 65(1): 129-134 (en inglés). The present paper deals with the morphological, anatomical El presente artículo se refiere a las características morfológicas, la structure of achenes in the East Asian species of Rhaponticum, estructura anatómica de los aquenios en las especies de Rhapon- Klasea Serratula and Synurus. The structure of pericarp epider- ticum, Klasea Serratula y Synurus en Asia oriental. Se han descrito mal cells, mesocarp, has been described, as well as the structure la estructura de células epidérmicas del pericarpio, y el mesocar- of testa epidermal cells. The specific characters of the genera, as pio, así como la de la testa de las células epidérmicas. También well as the identification characters of the species, are described. quedan descritos los caracteres específicos de los géneros, así Keywords: Asteraceae, Cardueae, achene, anatomic structure. como los caracteres de identificación de las especies. Palabras clave: Asteraceae, Cardueae, aquenio, estructura anatómica. Introduction of the achene’s integuments – crystals and secretory ducts. Calcium oxalate crystals were revealed in the The morphological and anatomic structure of ach- inner parenchyma. Occurrence of calcium oxalate enes in the tribe Cardueae Cass. is of great importance crystals in the inner parenchyma layer of pericarp in for hierarchial classification of the superspecific taxa. the Cardueae had been mentioned (Hanausek, 1911; One of the first papers on achene anatomy of Aste- Dormer, 1961; Singh & Pandey, 1984) as well. raceae was published by Lavialle (1912), who had The morphological and anatomic structure of ach- studied about 83 species of 15 genera: Arctium L., enes has been used in solving some taxonomic prob- Carduncellus Adans., Carduus L., Carthamus L., Cen- lems in the tribe Cardueae (Dittrich, 1968a; 1968b; taurea L., Cnicus L., Cousinia Cass., Crupina Cass., 1968c, 1970, 1977, 1985). Besides, there are quite a Cynara L., Galactites Moench, Jurinea Cass., Onopor- number of papers that cover morphological and dum L.,Saussurea DC., Serratula L. and Silybum anatomic structure of achenes in individual species Adans. Major achene characteristics, including the of the tribe or in groups of species (Fourment & al., testa’s epidermis pattern, of the representatives of the 1956; Gochu, 1973; Karawya & al., 1974; Chargo- tribe were described in details. At the beginning of glyan, 1975; Namba & al., 1975; Pandey & Singh, achene development the epidermal cells are isodia- 1977; Cherneva & Shurukhina, 1979; Wagenitz & al., metrical in shape, in the course of its development 1982; Pérez-García & Duran; 1987; Chernik, 1984; they stretch in the radial direction, their walls get Häffner, 2000). greatly sclerified. The radial elongation begins near the micropyle and spreads towards the subchalazal Materials and methods region. There are no cells directed perpendicularly to the tangent, they are inclined to the micropyle. We have studied morphology and anatomy of ach- Lavialle also paid great attention to specific structures enes of East Asian representatives of the subtribe 130 E.V. Zarembo & E.V. Boyko Centaureinae (Cass.) Dumort: Klasea Cass., Rhapon- manshurica) to 80 µm (Klasea centauroides) in the in- ticum Vaill. and Serratula (Leuzea DC., Stemmacantha tercostals area (Figs. 2, 3, 4). (Cass.) and subtribe Carduinae (Cass.) Dumort. Achenes of Synurus deltoides are characterized by -Synurus Iljin. In the Far East of Russia the genus Ser- very thick pericarp and comparatively thin testa. The ratula is represented by S. manshurica Kitag. The embryo is mostly protected by pericarp and to a lesser genus Klasea is represented by twos species: Klasea extent by testa. The thickness of mature achene in- centauroides (L.) Cass. and K. komarovii Iljin. The teguments varies from 485-540 µm in the intercostals genus Rhaponticum is represented by two taxa: area, and to 640-660 µm on the ribs due to the differ- Rh. uniflorum (L.) DC. and Rh. satzyperovii Soskov. ent thickness of pericarp, which determines the oc- The genus Synurus is represented by 1 species, Synu- currence of numerous longitudinal ribs on the achene rus deltoides (Ait.) Nakai. surface (Fig. 1). For the micromorphological observations, achenes The studied representatives of Rhaponticum are were softened in a solution of glycerine, ethanol and characterized by relatively thick pericarp and thick water (1:1:1) for a few days, embedded in paraffin and testa. The embryo is equally protected by pericarp cut by microtom. Sections were cut to a thickness of 8- and testa. The mature achene integument thickness 15 µm. Longitudinal and cross sections were stained varies due to the different thickness of pericarp, in safranin. which determines the occurrence of numerous longi- tudinal ribs on the achene surface. In the region of Results and Discussion the large strands of mechanic tissue located around conducting bundles the thickness of the achene in- Achene integument teguments reaches 270 -360 µm on the ribs, and from 200 to 270 µm in the intercostals area. In the upper Achenes of the subtribe Cardueae are character- part of achene the thickness of the integument is 500- ized by thick multilayer integuments and a palisade 590 µm – due to enlargement of parenchyma cells in row of macrosclereids, which clearly sets apart the the peripheral region of the pericarp, as a result den- species of the subtribes Cardueae and Centaureinae ticles on the margin of the achene apex are formed. from the representatives of the subtribe Carlininae. The pericarp thickness varies from 25-80 µm in Achenes of the studied species of Klasea and the intercostals area, and to 100-160 µm on the ribs Serratula are characterized by equally developed (Fig. 5). pericarp and testa. The general thickness of the ma- ture achene integuments varies from 100 to 230 µm Topography of epidermal cells of pericarp due to the different thickness of pericarp. In the re- gion of the large strands of mechanic tissue located Mature pericarp is represented by exocarp and around conducting bundles, the thickness of peri- mesocarp. In the species of Serratula the exocarp is carp varies from 60-65 (S. manshurica) to 135 µm formed by one row of cube-shaped epidermal cells (S. (Klasea centauroides), and from 25-40 (Serratula manshurica). In Klasea these cells are oval (S. centau- ab Fig. 1. Synurus deltoides: a, cross section of achenes; b, longitudinal section of achenes; ET, epidermal cells of testa; E, endosperm, H, hydrocytes. Scale bar: 0,1 mm. Anales del Jardín Botánico de Madrid 65(1): 129-134, enero-junio 2008. ISSN: 0211-1322 Carpology of some East Asian Cardueae 131 a b Fig. 2. Klasea centauroides: a, cross section of achenes; b, longitudinal section of achenes; ET, epidermal cells of testa. Scale bar: 0.1 mm. ab Fig. 3. Serratula manshurica: a, cross section of achenes; ET, epidermal cells of testa; b, epidermal cells of testa (cross section). Scale bar: 0.1 mm. Fig. 4. Klasea komarovii (cross section of achenes): ET, epider- Fig. 5. Rhaponticum uniflorum (cross section of achenes): ET, mal cells of testa. Scale bar: 0.1 mm. epidermal cells of testa. Scale bar: 0.1 mm. Anales del Jardín Botánico de Madrid 65(1): 129-134, enero-junio 2008. ISSN: 0211-1322 132 E.V. Zarembo & E.V. Boyko roides) or rectangular (S. komarovii) (cross section). sclerenchyma cell walls reaches 2.5 µm. The parenchy- The epidermal cells of mature achenes of S. manshuri- matous cells at the border with testa also undergo in- ca are thin-walled, cube-shaped, 10-25 µm wide and tensive incrassation; in this region they are also repre- 8-15 µm high. In Klasea centauroides the epidermal sented by typical sclerenchyma cells arranged in 1-2, cells are oval, slightly radially elongated, with uni- rarely 3, rows. The cell diameter is 7-8 µm. The con- formly thickened walls, 12-15 µm high and 13 µm ducting bundles of pericarp are located closer to testa. wide; in Klasea komarovii the cells are rectangular, 4-6 µm high and 10-25 µm wide, tangentially elongat- Secretory ducts ed, the cell lumen is filled up with phlobaphenes, therefore the achenes are dark brown. Secretory ducts are of great importance in the tax- The exocarp of the representatives of the Rhapon- onomy of the Cardueae s. l. (Dittrich, 1977). Thus, ticum is formed by one row of epidermal cells. From Lavialle (1912) pointed out that in Serratula coronata the outside the fruit is covered with thick smooth cu- L. the pericarp is entirely lacking in secretory ducts ticle up to 10 µm wide. The epidermal cells are large, during all stages of achene development, which dis- rectangular, tangentially stretched, thin-walled, 25 µm tinguishes it from the other species of Serratula such wide and 15 µm high (cross section), the cells are rec- as S. tinctoria L. Secretory ducts are also absent in tangular in longitudinal section, with inclined radial species of Klasea. Secretory ducts have been found walls, up to 55 µm long, the lumen of some cells is in the species of the genera Amberboa (Pers.) Less., filled up with phlobaphene. Carthamus (Chauhan, 1972; Singh & Pandey; 1984), The epidermal cells of Synurus deltoides are cube- Centaurodendron Johow and Yunquea Skottsb. (Carl- shaped, 12 -15 µm high and 10-18 µm (cross section) quist, 1958), Serratula, and species of some sections of wide, rectangular in longitudinal section, up to 25-40 Centaurea (Dittrich, 1977).