Phytolith morphology and biogenic silica concentrations and abundance in leaves of Chionochloa (Danthonieae) and Festuca (Poeae) in New Zealand

Abstract

Biogenic silica concentrations and phytolith morphology and abundance in green leaf material are described in 34 species/subspecies of Chionochloa (Danthonieae) and nine species/subspecies of Festuca (Poeae). A dry-ash technique was used to extract biogenic silica from mature leaves from plants grown in potting mix. Phytolith morphology and abundance were characterised by scanning electron microscopy and light microscopy, respectively. Biogenic silica concentrations were lowest (<1%) in Chionochloa bromoides, C. rubra ssp. occulta, and Festuca multinodis and reached levels of c. 7% in Chionochloa defracta and Festuca ultramafica, two serpentine endemics. Cluster analysis showed that replicate samples of taxa were classified together in 70% of cases. Ordination of phytolith types identified a major gradient based on the presence/absence of panicoid and chloridoid types. A secondary gradient was related to the frequency of chionochloid, truncated cone, and other short-cell phytoliths. Chionochloa taxa fall into 3 categories on the basis of the presence of panicoid (8 taxa) or chionochloid (11 taxa) phytolith types, or the absence of both (14 taxa). Species of Festuca had relatively high frequencies of points compared with Chionochloa, and absence or low frequency of dumbbell and chionochloid types. There was more interspecific variation among species of Chionochloa than in Festuca. © 2004 Taylor & Francis Group, LLC.