Inflorescence and floral development 
of Carnarvonia (Proteaceae) 
Andrew W. Douglas 
749 
Abstract 
Douglas, Andrew W. (Royal Botanic Gardens, Melbourne, Birdiuood Avenue, South Yarra, Victoria, 
3141, Australia) 1996. Inflorescence and floral development o/Carnarvonia (Proteaceae). Telopea 6(4): 
749-774. Carnarvonia araliifolia is an endemic of north-east Queensland and the sole member of 
the subfamily Camarvonioideae in Proteaceae. The inflorescence structure is atypical compared 
to the relatively simple racemiform architecture found in the other taxa of the family (including 
Grevilleoideae that has flower pairs). There is variability in numbers of flowers on a given axis, 
irregular branching of inflorescence axes, positions of flowers within an axillary module, numbers 
of flowers at a node on the principal axes, and the cauliflorous, axillary and/or terminal location 
of flowering regions on a branch. Carnarvonia has been hypothesized as having shared a common 
ancestor either with or within Grevilleoideae. Developmental evidence is examined to better 
define and elucidate the morphogenetic processes involved in the complex architecture of the 
inflorescence and flowers including the fundamental units of construction within a metameric 
conceptual framework. Likewise, the developmental evidence is used to examine the hypotheses 
of morphological derivation of the inflorescence as inferred from phylogenetic hypotheses. The 
inflorescence structure is interpreted as a paniculiform-raceme although terminal flowers are 
present on axillary inflorescence branches. There is variation within the developmental 
programme of the first three metamers of a subunit or axillary inflorescence branch that differs 
from the variation present in other Proteaceae and an inflorescence branch can vary in the 
number of flowers that develop. In the terminal flowers of a module, the first tepal is initiated 
in a position that follows the phyllotactic continuity of each subunit (2/5), the first tepal being 
initiated in a predictable position based on the position of the preceding bract primordium. The 
carpel is initiated in a lateral position, closest to both the first initiated stamen and tepal, thus 
maintaining the phyllotactic continuity in the flower. The ontogenetic events involved in 
inflorescence development in Carnarvonia clarify its morphological organization and provide 
morphological evidence of the derivation of the inflorescence form from a single-flowered, 
perhaps racemiform, ancestor. 
Introduction 
Carnarvonia araliifolia F. Muell. (1867) is the sole member of the genus and is endemic 
to north-east Queensland (Hyland 1995). Originally, the genus was placed in 
Grevilleoideae (Engler 1889) based on the dehiscent follicle and winged seeds and in 
the tribe Macadamieae by Venkata Rao (1971) based on the regular flowers. Currently, 
the genus is placed in a subfamily of its own, Camarvonioideae (Johnson & Briggs 
1975) on the basis of several unique characters like the loosely organized racemo- 
paniculate inflorescence, fmit structure, 'partly digitate, partly pinnate and partly 
first-degree, partly second-degree division of the leaves' (Johnson & Briggs 1975, 
p. 106-107), and several hypothetically independently derived characters or homoplasies 
such as the absence of liypogynous glands, and the the presence of two hemitropous 
ovules. Carnarvonia is also excluded from Grevilleoideae due to the fact that it lacks 
the grevilleoid flower pair condition (two flowers subtended by a common bract 
along the main axis; Johnson & Briggs 1975). In Johnson & Briggs (1975), Carnarvonia 
is hypothesized to be derived from a common ancestor of Grevilleoideae. 
