A survey on the intraclear inclusions in the Schrophulariaceae and their systematic significance

A survey of nuclear inclusions in chlorenchyma cells is given for 290 taxa of the Scrophulariaceae, covering 72 genera; 172 are new data and the remainder are from previous reports by the author. In addition to the 5 types of nuclear inclusions already determined by their different ultrastructural morphology — amorphous (A), lamellar (L), fibrillar (F), tubular (T), and crystalline (C) — and to subtypes C2, three new subtypes — A2, L2, T2 - specific to certain genera or small groups of genera are reported. These new subtypes are described in detail and their distribution in the family discussed. Although the proteinic nature was unquestionably demonstrated, the origin and function of plant nuclear inclusions is far from being understood. In the Scrophulariaceae they have been recognized in 242 out of 290 taxa studied (83.4%), in a total of 60 out of 72 genera (83.3%). On the basis of the occurrence and qualitative distribution of the nuclear inclusions, the family can be subdivided into four main group: 1) with lamellar inclusions, 2) with amorphous inclusions, 3) with inclusions other than those in the two former groups, and 4) with no nuclear inclusions. The relationship between the distribution on the nuclear inclusions throughout the family and the current systematic arrangement into subfamilies are analyzed and the transfer of some genera to different tribes or to a tribe of their own is proposed, e.g., in the case of Mimulus, Leucocarpus, Halleria, Russelia, Angelonia, Rehmannia , and Campylanthus . Finally, a possible evolutionary trend of the different types of nuclear inclusions based on their structural complexity and on the occurrence in allied families is offered.