THE FLORAL MORPHOLOGY AND VASCULAR ANATOMY OF THE HAMAMELIDACEAE: SUBFAMILY LIQUIDAMBAROIDEAE1

Inflorescence and floral morphology and floral vascular anatomy of the subfamily Liquidambaroideae (Liquidambar L., Altingia Nor.) are described. The inflorescence appears to be a greatly condensed compound raceme with proximal pistillate heads and distal staminate heads. Functionally pistillate flowers contain sterile or even fertile stamens. Functionally staminate flowers may show evidence of partially developed gynoecia. There is no morphological or anatomical evidence of sepals or petals. In functionally pistillate flowers a cycle of sterile phyllomes of uncertain nature (staminodia?, disc lobes?) is inserted on the hypanthium between the stamens and carpels of the partly inferior ovary. In pistillate flowers the stamens derive a single trace and the phyllomes a ramifying system of bundles from hypanthial trunk bundles. Each carpel contains a dorsal and two ventral bundles. Numerous ovules on each carpel margin receive traces from the ventral bundles. The gynoecium is interpreted as the most primitive within the Hamamelidaceae, and subfamilial status of Liquidambaroideae, rather than segregation as the family Altingiaceae, is supported. There has been an increase in interest and discussion in recent years concerning the nature and origins of the "Amentiferae"-a group now accepted by a majority of modern systematists as being made up of highly advanced and specialized taxa-and how they relate to more primitive groups of angiosperms. Central to this problem are the nature and position of the family Hamamelidaceae, which occupies an intermediate position in the various theories and phylogenetic schemes that have been put forth. However, any considerations of the phylogenetic position of the Hamamelidaceae, and of the trends of specialization both within and without the family, must begin with a reasonably clear understanding of which members of the family are primitive, or most nearly so, and which are advanced. At present, opinion is divided on this point and on circumscription of the family. This is due to the