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TAXON 57 (3) • August 2008: 893–906 Passalacqua & al. • Biosystematics of the Jacobaea maritima group

Fig. 7. Scatter plots of first three Principal Coordinate axes of selected cases in J. maritima s.l. Symbols as in Fig. 4. A, first
and second PCo axes; B, first and third PCo axes.

127.528, Table 6) and capitulum hairiness (H = 125.341,
Table 6). In fact, J. maritima is densely pubescent, J. bi-
color and the Levanzo group pubescent, and J. gibbosa
glabrescent to completely glabrous; these characters clearly
link the Levanzo group to J. bicolor, casting some doubt
on the distinctiveness of the Levanzo unit. The latter also
approaches J. bicolor in the longer capitulum involucre (H
= 66.833, Table 5), and in the densely pubescent adaxial
leaf surface (H = 79.420, Table 6). On the other hand, the
Levanzo group approaches J. maritima in the lower stem
height (H = 61.015, Fig. 6), the larger involucre (H = 55.923,
Table 5; this occurrence had already been noted by Pign-
atti, 1982, in relation to J. maritima and J. nebrodensis),
the pubescent to densely pubescent abaxial surface (H =
72.412, Table 6), and the lower inflorescence branching,
with respect to all the other populations. Indeed the statisti- Fig. 8. Dendrogram of selected cases in J. maritima s.l. Hi-
cal analysis showed that these two populations have, on av- erarchical clustering, using Incremental Sum of Squares
erage, fewer primary (H = 47.768, Fig. 9A) and secondary agglomerative method.
branches (H = 55.180, Table 5); not surprisingly, we found
a similar pattern in the capitulum number (Fig. 9B). tomentose on the abaxial surface, and arachnoid on the
Together with morphometric analysis, we evaluated adaxial one; J. bicolor is whitish to grey-tomentose on the
other qualitative data that could help in discriminating abaxial surface and pubescent to densely pubescent (but
taxonomic units. Involucres of capitula have been used in never arachnoid) on the adaxial; J. gibbosa has a grey
the past to characterise J. gibbosa, which often shows (as to greenish indumentum on the abaxial surface and is
the specific epithet suggests) gibbosity at the base of the pubescent to glabrescent on the adaxial, and the Levanzo
involucre. Field and herbarium observations allowed us group shows a similar pattern to J. bicolor. In J. ambigua
to note that this feature is not constant and, above all, not s.l., J. ambigua s.str. is grey-tomentose on the abaxial sur-
exclusive to this taxon. On the contrary, the hair cover- face and pubescent to somewhat arachnoid on the adaxial,
age of the leaf surface seemed to show some qualitative while J. nebrodensis is white to grey tomentose on both
differences. In J. maritima s.l., J. maritima is whitish- surfaces.

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