|Publication Type:||Web Article|
|Year of Publication:||2003|
|Authors:||Buzgo, M, Soltis, DE, Soltis, PS|
|Keywords:||Juncaginaceae, Alismatales, flower development, perianth, tepal|
Previous studies on the perianth development of basal monocots argued that the differentiation of tepals and bracts, or of sepals and petals had not fully evolved in Acoraceae and some Alismatales (namely the lineage comprising Juncaginaceae and Potamogetonaceae). Described similarities between Acorus and Triglochin were challenged by two hypotheses:1) What was described as a "flower" in Triglochin is a pseudanthium (an inflorescence looking like a flower), and the "perianth" consists of bracts;2) Triglochin does not have an abaxial outermost "tepal" reminiscent of a flower-subtending bract, but flower development commences with two lateral (or adaxial) tepals.We illustrate the flower development of Triglochin maritimum in the framework of other Juncaginaceae (Triglochin, Maundia, Tetroncium). The developmental genetics of the perianth in basal monocots is discussed with respect to "organ identity" and "homology". Up to now, the two challenging hypotheses are not supported by our data. Triglochin has no pseudanthium, and the perianth consists of tepals. Flower development is unidirectional with a leading abaxial tepal. However, there are putative reductions in the flowers within a single inflorescence, within the genus Triglochin, as well as the entire family Juncaginaceae.