Fundamentals of Plant Morphology and Plant Evo-Devo (Evolutionary Developmental Morphology)

Abstract

Morphological concepts are used in plant evo-devo (evolutionary developmental biology) and other disciplines of plant biology, and therefore plant morphology is relevant to all of these disciplines. Many plant biologists still rely on classical morphology, according to which there are only three mutually exclusive organ categories in vascular plants such as flowering plants: root, stem (caulome), and leaf (phyllome). Continuum morphology recognizes a continuum between these organ categories. Instead of Aristotelian identity and either/or logic, it is based on fuzzy logic, according to which membership in a category is a matter of degree. Hence, an organ in flowering plants may be a root, stem, or leaf to some degree. Homology then also becomes a matter of degree. Process morphology supersedes structure/process dualism. Hence, structures do not have processes, they are processes, which means they are process combinations. These process combinations may change during ontogeny and phylogeny. Although classical morphology on the one hand and continuum and process morphology on the other use different kinds of logic, they can be considered complementary and thus together they present a more inclusive picture of the diversity of plant form than any one of the three alone. However, continuum and process morphology are more comprehensive than classical morphology. Insights gained from continuum and process morphology can inspire research in plant morphology and plant evo-devo, especially MorphoEvoDevo.

Polycotyly: How Little Do We Know?

“…Such diverse cotyledon morphologies were considered to be abnormal and provided few answers, but revealed complexities, in terms of our understanding of the modes of increases and decreases in cotyledon number [ 5 ]. It also became obvious that classical morphology analysis has its limits, as continuum and process morphologies need to be considered to analyze cotyledon complexity [ 59 ]. The idea of evolutionary developmental morphology (e.g., [ 60 ]) may be applied to analyzing cotyledon morphological variation.…”

Morphological and taxonomical treatments of fruits in the subclass Rosidae Takht. of the flora of Ukraine

“…(69/379-430) (Fedoronchuk, 2018) -legume (pod, ukr. bib), multiseeded superior monocarpium (Kaden, 1965;Roth, 1977;Van der Pijl, 1982). Following Kaden (1965), legume can be:…”

“…• bivalvate, dorsi-ventrally dehiscent, covered (most genera and species), or envelo ped (Ononis L.); • transversely septated, covered, dorsi-ventrally dehiscent (Faba Mill., Phaseolus L.); • indehiscent uncovered (Gleditsia L.); • folliculate, enveloped, ventrally dehiscent (many Trifolium Tourn. ex L. species, except those listed beneath); ventral dehiscence is slow, often incomplete or missing (Roth, 1977); • enveloped, circumscissile dehiscent (Trifolium alpestre L., T. borysthenicum Grum., T. incarnatum* L., T. pratense L., T. rubens L.); • utriculate, enveloped, rupturing (Trifolium arvense L., T. campestre Schreb., T. dubium Sibth., T. aureum Pollich); • articulated (loment fruit), covered (Coronilla L., Securigera DC., Hedysarum L., Hippocrepis L., Ornithopus L.); • achene-like, indehiscent, covered (Amorpha L., Glycyrrhiza echinata L., Medicago lupulina L., Melilotus L., Onobrychis Mill. ), or enveloped (Anthyllis L.) (Kaden, 1965).…”

“…have one-to few-seeded indehiscent legume while other species of Trigonella L. and Medicago L. have hardly dehiscent or coiling fruit (helicoid pod) (Roth, 1977); • pseudo-bilocular, covered (Astragalus L., Oxytropis DC. ), with the longitudinal false septum of different origin (Roth, 1977). Fruit is ventrally dehiscent (А. dasyanthus Pall., О. pilosa (L.) DC.…”

“…Ovary stipitate, placentas axile, globose; capsule septicidal (Graham & Graham, 2014). • In Punica L. -fruit is an irregularly dehiscing capsule with juicy seeds and persistent calyx; ovary -inferior, with two or possibly three concentric whorls of carpels; axile placentation, but due to the receptacle invagination after insertion of carpels, placentas of the outer carpels shift to the ovary wall and thus become parietally located (Roth, 1977). Other names of the Punica fruit are balausta (ukr.…”