Taxonomic significance of morphological and elemental characteristics of
achenes of Artemisia genus from Turkey
Abstract
In the study, the achene macro and micro morphological characters of the
genus Artemisia distributed in Turkey have been researched with
the target to know systematically important carpological structures for
the examined species. Color, shape and dimension of achene have
macro-morphologically shown variations. The examined achenes are
separated into 4 shapes; fusiform-oblong, oblong, oblong-ovate and
ovate. Oblong-ovate is the most common type. However, oblong is typical
form for A. abrotanum. Achene dimensions range from 0.62 mm to
2.48 mm in length, from 0.30 mm to 1.21 mm in width. As A.
santonicum subsp. patens is of the largest achenes , A.
annua and A. verloitorum have the smallest achenes. Also,
carpopodium diameter vary between 0.10 mm and 0.19 mm. The largest
carpopodium diameter is found in taxa A. fragrans and A.
taurica var. vanensis , while the narrowest one is A.
alpina species. Achene surfaces of the examined taxa are
micro-morphologically assessed, and the substantial differences are
noticeably detected on behalf of the surface structures for instance,
surface ornamentation, anticlinal and periclinal cell walls, epidermal
cells and presence of secondary structures of the achenes. Surface
ornamentation is separated into 10 types: irregularly sulcate, regularly
sulcate, ruminate, sulcate-scalariform, rugose, favulariate, slightly
sulcate, alveolate, tuberculate and reticulate. The most common types
are irregularly sulcate (in 7 taxa) and regularly sulcate (in 7 taxa),
while ruminate (in A. abrotanum), rugose (in A.
chamaemelifolia), favulariate (in A. arborescens), alveolate (in
A. santonicum subsp. patens), tuberculate (in A.
taurica var. vanensis) and reticulate (in A.
bashkalensis) ornamentation types are found as taxon-specific. A
percentage comparison of the elements in the achene pericarp of the
studied taxa have performed with SEM-EDS. Accordingly, pericarps in taxa
include C, Ca, K, Mg, Cl, Si, Na and S elements. The most common seen
element is C, which ranges from 77.4 (in A. austriaca) to 96.2
(in A. absinthium). Na element is observed only in A.
santonicum subspecies and A. arborescens species. On the other
hand, S element is found in low amounts only in A. alpina
species. In the taxonomy of the genus Artemisia, the achene
morphological characters are very significant characteristics that
disclose inter-specific relations among the examined taxa. Moreover, a
dichotomous key is offered for the identification of the studied taxa
based on achene characters.