Seedling characteristics in the Casuarinaceae

Abstract

Seedling characters and their distributions within the genera of the Casuarinaceae and their sections are described for 45 taxa in the family representing three of the four genera and all 14 of the currently recognised sections in Allocasuarina. The cotyledons in Gymnostoma are petiolate, a feature absent from the other taxa examined. There were no obvious genus-level seedling features distinguishing either Casuarina or Allocasuarina, although red-purple cotyledons at senescence are common in Casuarina but rare in Allocasuarina. Several features are informative at the sectional level: suppression of secondary cotyledon branches is only found in Allocasuarina sects, Oxypitys, Platypitys, Echinopitys and Ceropitys, as were abortion of the primary shoot and divergent tooth apices, the latter two characters otherwise found only in A. monilifera and A. microstachya. Seedlings of sect. Ceropitys showed a distinctive growth habit making them look like Lycopodium shoots with outgrowths resembling microphylls.