Lavatera oblongifolia is a small perennial shrub 60 – 150 cm tall, branching from a woody base, with erect, turning stems. Its upper leaves are generally erect and more or less folded, while lower leaves are patent.
It bears single flowers in the leaf axils of indeterminate flowering stems, which are entirely homologous with determinate flowering stems in closely related species such as Lavatera olbia – although these are often described as ‘leafy inflorescences’. The fasciculate axillary inflorescences of species such as Lavatera triloba represent a multiplication of these. The epicalyx in Malvaceae (Malvoideae) is understood to be derived from the involucral bracts of an ancestral cymoid inflorescence reduced to a single flower.
Its diploid chromosome number is 42, which is presumed to be derived from hexaploid ancestors, as the base chromosome number for Lavatera is 14 – as found in the type species Lavatera trimestris.
The leaves are:
The petioles are up to 15 mm, and much less than half as long as the blade
The stipules are:
The flowers are:
The petals are:
The calyx is:
Sepal lobes are:
The bracteoles are:
The fruits are schizocarps divided into 16 – 20 mericarps.
The mericarps are:
The seeds are brown, asymmetrically oblong and kidney-shaped.