Christoph Oberprieler The Systematics of Anthemis L. - Herbmedit.org

Bocconea 9 - 1998 31
The styles are also very uniform throughout the genus. The base of the style becomes
usually swollen and hardened due to enlarged and sclerified cells. Two vascular bundles
run through the cylindrical and glabrous style shaft and end in the stigmatic branches,
which are truncate-penicillate, bearing two separate lines of stigmatic papillae on the inside
and obtuse sweeping hairs at their apex. Usually the stigmatic branches contain elongate
resin ducts with a brown or orange content.
Achenes
Like the vast majority of Compositae, Anthemis has dry, monosperrnous fruits developed
from a bicarpellate coenocarpic inferior ovary, with the seed testa adhering to but not
coalescent with the pericarp. Although the ovary of Compositae is inferior, the fruit wall is
generally terrned pericarp, and its structures usually been described in the terrns of epi-,
meso- and endocarp, by analogy to the fruit wall in a superior ovary. Following Wagenitz
(1976) and Roth (1977), the terrn "achene" as defined by Candolle (1813) is used in the
present work for this type of fruits. The term "cypsela" was introduced by Mirbel (1815)
and is frequently used in Anglo-Saxon and Nordic synantherologicalliterature (e.g. Humphries
1979, Kiillersj6 1991, Anderberg 1991a, b, c, Bremer & Humphries 1993, Bremer
1994). However, exceptions are found (e.g. Hansen 1991), and in Anglo-American literature
the term "achene" still prevails (e.g. Stuessy 1968, Funk 1982, Jansen 1985, Panero
1992).
Dating back to the thorough studies of Briquet (1916), the paramount importance of
achene morphology and anatomy for the taxonomy of Anthemideae and for the delirnitation
of genera in this tribe is well known. In Anthemis the achenes provide some very
important diagnostic features for the subdivision of the genus and the circumscription of
species groups.
Achenes of ray florets were found to be rather similar in most studied representatives of
Anthemis subg. Anthemis. They are usually subcylindrical or fusiforrn in shape and slightly
bent inward. Being tightly confined to the trigonal space between the achenes of peripheral
disc florets and their pales and the flat inner surface of the inner involucral bracts, they are
roundish to triangular in cross section, with a flattish abaxial and a rounded or edged adaxial
face. The achenes of ray florets usually have (8-)9( -lO) ribs which are rather indistinct
on the adaxial but more prorninent and in some species even tuberculate on the
abaxial face. Like the achenes of disc florets, they are usually beset with mucilage cells on
their ribs and by glands in the intercostal furrows. The apical plate is usually bordered with
a ridge that in some species is adaxially protracted into a membranous auricle up to 0.3
mm long. The achenes of ray florets in A. austriaca (A. subg. Cota), unlike those in
A. subg. Anthemis, strongly resemble achenes of disc florets in being conspicuously flattened
dorso-ventrally.
The achenes of disc florets provide a greater number of characters of use for species
delirnitation and supraspecific classification than the achenes of ray florets. While essentially
homomorphic, the achenes'of disc florets tend towards heteromorphy in most of the
species due to overall structural reduction from the larger peripheral to the smaller centraI
achenes. In some species, the differences between achenes of marginaI and centraI disc
florets are particularly well marked: In Anthemis mauritiana and A. arvensis the achenes
of peripheral disc florets are extremely stout and subcylindrical or obconical, while the
centraI achenes are much more slender and obconical-obovoidal. In most N African An-