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

28 Oberprieler: Anthemis in N Africa
A further character of some taxonomic importance is the colour of the pale tips. In taxa
of A. sect. Hiorthia they are often tinged with dark brown or even black (e.g.
A. pedunculata, A. eretica subsp. columnae, A. punctata), but such tinge is lacking in
populations of A. maritima and some plants of A. punctata subsp. punctata. Pales of
A. monilicostata and some populations of A. ubensis also end in blackish tips.
The strength of attachment of pales on the receptacles is also a useful character. In most
of the species studied, at least the peripheral pales persist on the receptacles even after the
dissemination of achenes. In A. sect. Bourgaeinianae, however, pales fall off very easily,
so that after dissemination receptacles are left completely naked.
The hypothesis of Stuessy & Spooner (1988), that one of the functions of pales may be
the protection of flowers, ovaries, and achenes from apical and lateral insect attack, is
plausible though the adaptive significance may be less obvious in Anthemis than in the
Heliantheae they had studied.
Ray florets
Ray florets of N African Anthemis have few taxonomically relevant characters. Corollas
are divided into a lower tubular part and an upper, flat corolla limb. The tubular part is
usually flattened dorso-ventrally but may get somewhat inflated and winged at maturity. In
most species the tubular part and the abaxial face of the limb bear biseriate glands. Four
vascular bundles are found in the tubular part of the ray florets. In the proximal region of
the limb, several minor traces that end blindly split off from these main bundles which
continue up to the 3-lobed apex of the limb where they anastomose. Baag0e (1977) studied
four representatives of the genus and found that the adaxial epidermis of their ray florets
corresponds to her "helianthoid type", consisting of more or less isodiamterical and papillose
cells without thickened walls. Contrary to her indications, the corolla glands are not
one-celled but correspond to the typical biseriate glands formed by usually eight cells that
are found all over the vegetati ve and fiorai parts of all Anthemis species.
The length and the colour of ray floret limbs may be taxonomically relevant. Most radiate
species are characterised by white ray florets, but those of Anthemis ser. Chrysanthae
are yellow, ranging from a saturated canary yellow (9A in Anon. 1966) in A. boveana,
A. chrysantha, A. maroccana, and A. tenuisecta to a pale yellow (3A in Anon. 1966) in
A. gharbensis. White ray florets are usually monochromous during flowering, but tend to a
brownish tinge at the base of the limb when withered. Limb length is diagnostic for some
closely related taxa, for instance A. maritima subsp. maritima (7.5-12.0 mm) and subsp.
bolosii (3.8-8.0 mm); A. boveana (7.0-14.0 mm) and A. chrysantha (2.1-7.0 mm); and
A. stipa rum subsp. stiparum (7.2-11.5 mm) or subsp. intermedia (7 .0-10.5 mm) and subsp.
sabulicola (4.5-8.5 mm). The width of ray floret limbs being fairly constant, variation in
length usually also affects the shape of the limb, which ranges from nearly circular to narrowly
elliptical or narrowly oblong.
Usually the florets are female and furnished with a style. In contrast to disc florets, the
style branches are often laterally enlarged and devoid of sweeping hairs, having lost their
function for pollen presentation. In Anthemis cotula, however, some plants with sterile ray
florets lacking a style were observed, along with others in which they are pistillate and
even fertile. Occasionally, in most species anther rudiments can be found in the tubular
part of the ray florets.