Echinocodon Hong,a New Genus of Campanulaceae and Its Systematic Position |
| |
| Authors: | Hong De-Yuan |
| |
| Abstract: | Echicocodon Hong (Wahlenbergieae); Gen. nov. Calyx 2-5-saepe 4-fidus; lobis utrinque 2-4-lobulis spiniformibus praeditis. Corolla tubulosa; ad medium parterm (3-) 4 (-5)-lobata. Stamina (3-) 4 (-5); libera; sed interse eonniventia; filamentis basi parum expansis. Ovarium fere inferum; 3-5-1oculare; stigmata 3-5; demum recurva; linearia; ovula ∞. Capsula globosa; 3-5-locularis; spice loculicide dehiscens; valvis calycis lobis alternantibus. Semina ∞ ; minima; ellipsoidea; obtuse triquetra.——Herbae perennes; lactesentes; radicibus palaribus crassiusculis. Folia alterna; pinnatipartita. Flores solitarii terminalesque vel 2-3 in cymam conferti. Genus monotypicum; in provincia Hubei Sinae cresens. Typus generis: Echinocodon lobophyllus Hong. Echinocodon lobophyllus Hong; sp. nov. plate 1 Herbae diffusae; omnino glabrae; radicibus palaribus ad 5 mm crassis. Caulis ad 40 cmlongus; ramosissimus. Folia alterna; petiolis 5-10 mm longis; laminis ellipticis; 5-20 mmlongis; 3-15 mm latis; basi anguste cuneatis; apice obtusis; pinnatisectis vel ad mediumpinnatipartitis. Flores solitarii terminales vel 2-3 in cymam conferti; pedicellis 1-5 cm longis. Calycis lobi ovato-lanceolati; 2-6 mm longi; lobulis spiniformibus exclusis 1-3 mm lati. Corolla purpureo-caerulea; tubulosa; 3-4.5 mm longa; ad medium (3-)4(-5)-lobata; lobis late ovato-diltoideis; ad 3 mm latis. Stamina inter se conniventia; filamentis liberis; 1.5 mmlongis; basi expansis; ciliatis; antheris oblongis; 1 mm longis. Stylus 1 mm longus; stigmatalinearia; demum recurva. Capsula globosa; 3-5 mm diam.; sed parte supera conica et 2 mmlonga. Semina minima; luteo-fusca; ellipsoidea; obtuse triquetra; 0.3 mm longa. China: Hubei Province; Yunxi County; near the town; 300 m alt.; 1 Jul. 1983. Ma Yuan-jun and Hong De-yuan PB83006 (holotype; PE); the same locality; 11 Jul. 1978; MaYuan-jun 3921. The new genus; Echinocodon Hong; shows its systematic position in the tribe Wahlenbergieae by the inferior ovary and capsule which loculicidally dehisces above the calyx andis closely related to the genera Codonopsis; Platycodon and Wahlenbergia; from all of whichit differs in having the calyx lobes with spinelike lobules and the pinnatisect or pinnatipartite leaves. From Codonopsis it differs also in having the linear stigma lobes; from Platycodon also in the capsule valves alternate with the calyx lobes and from Wahlenhergia also inhaving the 4(5)-colpate pollen grains. Meiosis in pollen mother cells was examined and; 8 bivalents in MI and 8 chromosomes in MII were always observed (Plate 2: 1-2). The chromosomt number is thus determined to be n=8. The pollen grains taken from the flowers which were fixed in the fields with CarnoyII fixative (6:3:1 absolute alcohol/chloroform/glacial acetic acid) were examined withoutfurther treatment under SEM; and under LM after acetolysis. The result shows that theyare oblate; 4(5)-colpate (Plate 2: 3-4); with colpi 10.5μm long and 2.5μm wide andwith a smooth colpus membrane (Plate 2: 5). The exine is 2-layered; with a distinct baculate layer (Plate 2:7-8). The sexine surface is covered with spinules almost regularly spaced; 0.6μm high and basally divided. The sexine between spinules consists of short ridges(Plate 2: 6). The new genus is closely related to the genera Codonopsis; Wahlenbergia and Platycodon from gross morphological point of view; but its pollen grains differ markedly fromall of them. The pollen grains in Codonopsis are longly 5-colpate; and with the sexine consisting of a low relief reticulum; those in Platycodon longly 5-colporate and those in Wahlenbergia 3-porate. The pollen type of the new genus Echinocodon with short colpi is thereforeprobably derived from the longly colpate type of pollen like that of Codonopsis or directlyfrom longly colporate type like that of Platycodon; and is likely more primitive than thatin Wahlenbergia. |
| |
| Keywords: | Campanulaceae Echinocodon E.lobophyllus Pollen Chromosome |
|
| 点击此处可从《植物分类学报：英文版》浏览原始摘要信息 |
|
点击此处可从《植物分类学报：英文版》下载全文 |
