Seed coat morphology and its systematic implications in Cyanea and other genera of Lobelioideae (Campanulaceae)

Recent surveys of seed coat morphology in Lobelioideae (Campanulaceae) have demonstrated the systematic utility of such data in the subfamily and led to a revision of the supraspecific classification of Lobelia. Expanding upo n these studies, we examined via scanning electron microscopy 41 seed acces sions, emphasizing lobelioid genera in which only one or no species had bee n examined. Most conformed to previously described testal patterns. However , five species of the endemic Hawaiian genus Cyanea, comprising the molecul arly defined Hardyi Clade, had a unique testal pattern there termed Type Fl , characterized by laterally compressed, almost linear, areoles with rounde d, knob-like protuberances on the radial walls at opposite ends. This offer ed a convenient synapomorphy for recognition of a clade originally defined on a molecular basis. A second unique testal pattern was found in the relat ed Hawaiian endemics Brighamia and Delissea, thus supporting their close re lationship. In this type (here termed Type G), the seed coal is irregularly wrinkled (rugose), creating broad, rounded ridges that run more-or-less pe rpendicular to the long axis of the seed and thus to the long axis of the t estal cells. Seed coal morphology also supported the monophyly of all 124 s pecies of Hawaiian Lobelioideae and their probable derivation from Asian sp ecies of Lobelia subg. Tupa. Additional studies supported close relationshi ps between (1) the neotropical genera Centropogon and Siphocampylus; (2) th e western American genera Legenere and Downingia; and (3) Jamaican Hippobro ma and Lobelia sect. Tylomium, a group endemic to the West Indies.