Verbena L., Glandularia Gmel., Junellia Moldenke, Lantana L. und Lippia L. (Verbenaceae) in Peru

The floristic revision of the following genera represented in Peru
– Verbena, Glandularia,and Junellia as well as Lantana and Lippia,
is presented. Understanding of generic and specific
interrelationships has been in part contributed to by three
collecting expeditions to Peru by the author. Novel characters have
been surveyed and the taxonomic boundaries re-assessed in the light
of this new information. Verbena, Glandularia and Junellia are
closely related to each other, as are Lantana and Lippia. The first
group has both herbaceous and woody members, varying between erect
and creeping representatives. Their inflorescences are constructed
of simple or branched spikes. The flowers have pentamerous fused
calyces, with hypocrateriform, or sometimes cylindrical, five-lobed
corollas. The ovary is bilocular, possessing an additional false
septum forming four elongated nutlets. The second group has only
woody members and, with one exception, are all erect. The
inflorescence is a homeothetic pleiostachys with first order
paraclades. The co-florescences are sited above a more or less long
inhibition zone on the peduncle, their fertile zones producing
dense arrangements of roughly spherical spikes. The ovary is also
bilocular,but one locule is very much reduced. The genus Lantana
produces a one- or two-seeded drupe, while Lippia develops two
nutlets. The generic separation of the Verbena-Glandularia-Junellia
group is problematic and has been the focus of much discussion in
the literature. The three genera are retained mostly as they stand,
based on the fruit structure and the seed morphology. In the later
stages of seed development the basal part of the ovary is slender
in Junellia and Verbena,and broad in Glandularia. Glandularia
species also have bigger seeds than taxa in the two other genera.
In Junellia the basal region of the style appears fused with the
ovary tissue. In all Verbena species the calyx is, at maturity, not
(or barely) longer than the nutlets, which are freely dehiscent,
releasing the seeds. In the two other genera the calyx at maturity
is distinctly longer than the nutlets and encloses them. Verbena
has a basic chromosome number of x=7, Glandularia x=5, and Junellia
x=10. To further clarify the intergeneric relationships of these
three genera a molecular analysis is highly desirable. The
separation of the individual species is based on the following
characters that have shown themselves to be stable: habit, peduncle
length and elongation at anthesis of the terminal inflorescence,
bract shape and size, and flower form. Leaf shape, leaf size, and
flower colour are have restricted value as species-defining
characters because of their high variability. Additionally to these
characters it is important in Glandularia species to note the
lengthened gland-bearing anther connective, while seed form is
significant in Junellia. The following species are represented in
Peru: Verbena cajamarcensis, Verbena clavata, Verbena fasciculata,
Verbena hispida, Verbena litoralis, Verbena parvula, Verbena
pogostoma, Verbena pubescens, Verbena villifolia,Verbena
weberbaueri,Glandularia cuneifolia, Glandularia laciniata,
Glandularia microphylla, Glandularia tenuisecta,Junellia aspera,
Junellia juniperina, Junellia minima. Two new species have been
found and newly described: Verbena cajamarcensis and Verbena
pubescens. Glandularia cuneifolia has been recombined from Verbena
based on seed characters. It is recognised that Glandularia
laciniata represents a number of different taxa. Although the main
centre of distribution is indeed in Southern Peru, it was
unfortunately not possible to come to any definitive conclusions
concerning this taxon. The genera Lantana and Lippia exhibit very
similar habits. They can be most easily and simply distinguished by
their fruits. The fruits of Lantana are either leathery or fleshy
drupes that, in contrast to Lippia, show a reduction from two to
one well-developed locules, resulting in two one-seeded nutlets.
Another good generic descriptor is the form of the calyx. All
Lantana species have praemorse calyces with a fringed margin, while
the peruvian species of Lippia have a (seemingly) two-lobed calyx.
The anthers of Lippia flowers are inserted in the upper half of the
corolla tube and reach the mouth of the tube. The anthers of
Lantana flowers are instead basally inserted in the corolla tube.
The co-florescences have, in Lantana a long, and in Lippia a very
short or occasionally non-existent, inhibition zone. Lantana
inflorescences always demonstrably elongate between anthesis and
fruit maturity, a feature that never occurs in Lippia. And finally,
Lippia has flowers which, at their largest, are only ever half as
big as Lantana flowers. Lantana species can be distinguished easily
using flower colour, the presence of fleshy or leathery drupes, the
extent of co-florescence elongation after anthesis, and from the
shape and size of the bracts. Lippia species are distinguished
using characters including the degree of incision between the two
lobes of the calyx, the presence of the extended anther connective
and the shape and size of the bracts. The basic chromosome number
for Lantana camara is x=11. The following Lantana and Lippia
species are represented in Peru: Lantana angustibracteata, Lantana
camara, Lantana cujabensis, Lantana radicans, Lantana reptans,
Lantana rugulosa, Lantana scabiosaeflora, Lantana sprucei, Lantana
tiliifolia, Lantana trifolia,Lippia alba, Lippia americana, Lippia
antaica, Lippia ferruginea, Lippia tayacajana. Lantana radicans was
found by Ruiz & Pavon and so labelled on the herbarium sheets,
although the name was never validly published. This species is
therefore newly described here. Among the studied herbarium
material a single sheet of Lippia boliviana, labelled from Peru and
collected by Haenke, was found. Haenke’s collection data,
especially geographical entries, are known to be unreliable and, as
this was not supported by any other material, it is assumed that
this species only occurs in Bolivia.