Evolution of Sesquiterpene Lactones in Angiosperms*

162 VICENTE DE P. EMERENClANO, MARIA AUXILIADORA C, KAPLAN AND 01-tO R, GOTTLIEB
Is, O
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UO
OLAU
OAPi
OAa~
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I ..... I
O.OO ¢1~0 ~ s O.O0
FIG. 8. CORRELATION OF /~= AND ~o VALUES FOR FAMIUES OF
ANGIOSPERMS CHARAC~RIZED BY THEIR SFGflNE INDEXES (of. Table
8). F(x a glossary of the th~e-lmt~r ~onyml m Tolde 11.
state (in Vemonieae) and skeletal specialization
(in Heliantheae) respectively. Reduction of oxidation
state and loss of skeletal specialization
followed in both cases (towards Mutisieae and
Astereae, respectively). This, however, is only a
working hypothesis. It will be necessary to insert
into this frame other micromolecular data
appearing as replacement characters, in order to
arrive at a clearer picture.
Finally, it was deemed desirable to verify the
strength of the present analysis in face of the
permanent flow of new information. A prioriit is
hoped that the system involving structural types
and averages of chemical characters, rather than
single compounds, should lead to more durable
conclusions. This seems to be the case.
The present analysis is based on data assembled
by Fischer et al. [2] and by Seaman [3]
which reviewed the literature up to 1982. Table 14
lists 50 species of Asteraceae the composition of
which became known subsequently. A comparison
of their sesquiterpene lactone types and
their EA s and EA o parameters with the analogous
data registered in Tables 12 and 9 is instructive.
Among the eight new species of Mutisieae
(Table 14) predominate compounds of type 1, a
feature shared indeed by Mutisieae, Vernonieae
and Heliantheae (Table 12). The two latter tribes,
however, are characterized by considerably
higher EA s and EA o values (Table 9). Among the
three new species of Vemonieae predominate
compounds of types 1 and 1.3. This feature and
the high EA o values of the species are indeed
consistent with the general characteristics of the
tribe, as well as of Eupatorieae and Heliantheae,
the species of the latter, however, possessing
higher F_A s values. Among the seven new
species of Eupatorieae predominate again compounds
of type 1.3 and, reciprocally,
differentiation from Vernonieae is difficult. The 10
new species of Heliantheae are distinguished, as
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,~
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IANT
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FIG. 9. CORRELATION OF F..A, AND £A= PARAMETERS FOR TRIOES OF ASTERACEAE BELONGING TO THE SUBFAMIUES CIO4ORIOIDEAE (~) AND
ASTEROIDEAE GROUP 1 ~) AND 2 (~|; ANO FOR APIACEAE (X). For a glossary of she ~4otmr ac~mtyms ~e Ta~e 12.