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494
TYCHO NOR LINDH
diagram. By intercrossings, liew combinations of Ihe achene tvpes
appéar in ihe heads and particularly Ihe oceurrence of Ihe 3-winged
and rostrate ones is subject to variations.
Lanza divided Ihe Calendula species into tower taxonomical units
(forma carpica) according to the presence or absence of winged and
rostrate achenes. Furthermore he look into consideration the length of
the beak and distinguished a type »longirostris» (LANZA 1919). In
accordance with this principle the species may thus be divided into six
biotype groups, viz. I. exalata rostrata, II. excdata longirostris, III.
cx-alata erostris, I V. (data rostrata, V. alata longirostris and VI. (data
erostris. In Calendula aegyptiaca and C. arvensis all Ihese six biotype
groups occur, hut in the remaining species and subspecies of the genus
their number is not so large.
The c y m b i f o r m tvpe of achene (type 2) is found in nearly
all the biotype groups of the Cidendula species. According lo Lanza,
this type may nevertheless be abseilt in C. Monardi and probably also
in C. maderensis, as il has never been observed in this species.
Since different biotypes of the Calendula species may lack one or
two of Ihe following tvpes of achenes: cymbiform, 3-winged and
rostrate, the question may be asked: Gån there possibly also be
biotypes in some Calendula species which lack annulate achenes that
otherwise always occur? 1 should not be surprised if such a form were
discovered in due course. lf it should prove to be hereditarily constant
and not merely an abnormity, no sharp delimitation will exist between
the genera Calendula and Osteospermum. That being the case, there
will no longer be anything lo prevent their being united lo form one
genus, liut the old genera should nevertheless be retained as subgenera.
In Ihe small species group Crassifoliae of Calendula, viz. C.
maderensis, C. maritima and C. Monardi, there is possibly reason to expect
biotypes lacking annulate achenes. Lanza describes the inner ray
achenes in these species as imperfecte annularia sinn aperto». They are
thus imperfectly nnnulate.
In my determination key lo the genera in the tribe Calenduleae
(I p. 32), I have stated that the inner ray achenes in Calendula are
annulate or imperfectly annulate with an open bow and that the
achenes in Osteospermum, ön the other hand, are straight or rarely slightly
incurved. The difference in the shape of the achenes in the two genera
is best illustrated by the following figures of slightly incurved achenes
in Osteospermum (I p. 179, fig. 16 a: p. 277, fig. 26 h: p. 348, figs. 36 a,
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