Echinocodon Hong, a New Genus of Campanulaceae and Its Systematic Position

Abstract

Abstract:

Echicocodon Hong (Wahlenbergieae); Gen. nov.

Calyx 2-5-saepe 4-fidus; lobis utrinque 2-4-lobulis spiniformibus praeditis. Corolla tu-

bulosa; ad medium parterm (3-) 4 (-5)-lobata. Stamina (3-) 4 (-5); libera; sed inter

se eonniventia; filamentis basi parum expansis. Ovarium fere inferum; 3-5-1oculare; stig-

mata 3-5; demum recurva; linearia; ovula ∞. Capsula globosa; 3-5-locularis; spice locu-

licide dehiscens; valvis calycis lobis alternantibus. Semina ∞ ; minima; ellipsoidea; obtuse tri-

quetra.——Herbae perennes; lactesentes; radicibus palaribus crassiusculis. Folia alterna; pin-

natipartita. 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 cm

longus; ramosissimus. Folia alterna; petiolis 5-10 mm longis; laminis ellipticis; 5-20 mm

longis; 3-15 mm latis; basi anguste cuneatis; apice obtusis; pinnatisectis vel ad medium

pinnatipartitis.

Flores solitarii terminales vel 2-3 in cymam conferti; pedicellis 1-5 cm longis. Caly-

cis lobi ovato-lanceolati; 2-6 mm longi; lobulis spiniformibus exclusis 1-3 mm lati. Corol-

la purpureo-caerulea; tubulosa; 3-4.5 mm longa; ad medium (3-)4(-5)-lobata; lobis la-

te ovato-diltoideis; ad 3 mm latis. Stamina inter se conniventia; filamentis liberis; 1.5 mm

longis; basi expansis; ciliatis; antheris oblongis; 1 mm longis. Stylus 1 mm longus; stigmata

linearia; demum recurva. Capsula globosa; 3-5 mm diam.; sed parte supera conica et 2 mm

longa. 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 Yu-

an-jun and Hong De-yuan PB83006 (holotype; PE); the same locality; 11 Jul. 1978; Ma

Yuan-jun 3921.

The new genus; Echinocodon Hong; shows its systematic position in the tribe Wahlen-

bergieae by the inferior ovary and capsule which loculicidally dehisces above the calyx and

is closely related to the genera Codonopsis; Platycodon and Wahlenbergia; from all of which

it differs in having the calyx lobes with spinelike lobules and the pinnatisect or pinnatipar-

tite leaves. From Codonopsis it differs also in having the linear stigma lobes; from Platyco-

don also in the capsule valves alternate with the calyx lobes and from Wahlenhergia also in

having the 4(5)-colpate pollen grains.

Meiosis in pollen mother cells was examined and; 8 bivalents in MI and 8 chromoso-

mes in MII were always observed (Plate 2: 1-2). The chromosomt number is thus de-

termined to be n=8.

The pollen grains taken from the flowers which were fixed in the fields with Carnoy

II fixative (6:3:1 absolute alcohol/chloroform/glacial acetic acid) were examined without

further treatment under SEM; and under LM after acetolysis. The result shows that they

are oblate; 4(5)-colpate (Plate 2: 3-4); with colpi 10.5μm long and 2.5μm wide and

with a smooth colpus membrane (Plate 2: 5). The exine is 2-layered; with a distinct bacu-

late layer (Plate 2:7-8). The sexine surface is covered with spinules almost regularly spa-

ced; 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 Platyco-

don from gross morphological point of view; but its pollen grains differ markedly from

all of them. The pollen grains in Codonopsis are longly 5-colpate; and with the sexine consis-

ting of a low relief reticulum; those in Platycodon longly 5-colporate and those in Wahlen-

bergia 3-porate. The pollen type of the new genus Echinocodon with short colpi is therefore

probably derived from the longly colpate type of pollen like that of Codonopsis or directly

from longly colporate type like that of Platycodon; and is likely more primitive than that

in Wahlenbergia.

Key words: Campanulaceae, Echinocodon, E.lobophyllus, Pollen, Chromosome

Hong De-Yuan. Echinocodon Hong, a New Genus of Campanulaceae and Its Systematic Position[J]. .

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Echinocodon Hong, a New Genus of Campanulaceae and Its Systematic Position

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