Leaf and seedling morphology: the two prospective parameters to trace phylogeny in apiaceae subfamily apioideae.

Abstract

Determination of phylogenetic affinity among the members of Apiaceae especially the subfamily Apioideae is much debatable. The morphological evidences on inflorescence, fruit and seed characters showed little concomitance with those derived from molecular parameters as far as groupings in clades are concerned. In the present study involving few selected Apiaceae members, a Dendrogram was computed and a putative evolutionary trend was outlined based on leaf margin insertion pattern and cotyledonary leaf features, general plant morphology as well as leaf surface micromorphology by SEM. The members of Apiaceae with broad-ovate pinnatifid to pinnatipartite leaves and ovate –lanceolate cotyledonary leaves were included in a distinct cluster but the members with pinnatisect – decompounds leaves and linear cotyledonary leaves were included in a separate cluster. Long Coriander (Eryngium foetidum) included in the subfamily Saniculoideae may represent the most primitive condition having simple entire leaf with spiny margin. The member like Long coriander might have served as progenitor stock from which Coriander, Celery, Parsley (all with ovate pinnatifid to pinnatipartite leaves) and Cumin, Fennel, Dill (all having pinnatisect to decompounds leaves with linear segments) might have originated as evidenced by gradual increase in marginal insertion. Similarly, gradual narrowing of ovate-lanceolate cotyledonary leaves might have given rise to narrow linear cotyledonary leaves. Leaf-margin insertion pattern and cotyledonary leaf features appeared to be promising in tracing phylogeny in Apiaceae especially in Apioideae. Simple entire leaf represents the primitive condition and evolution in Apiaceae supposed to have progressed towards gradual increase in marginal insertion leading to pinnately dissected, pinnatipartite and ultimately to decompound leaves with narrow linear segments. Dendrogram computed from morphological features showed concomitance with that phylogenetic trend as far as grouping and interrelationships of members are concerned. In the present study leaf margin insertion pattern and seedling morphology appeared to be instrumental in tracing the phylogeny in Apiaceae specially subfamily Apioideae while molecular systematics are not conclusive.