The gelatinous fibres of Caesalpiniaceae

Twenty-seven species of Caesalpiniaceae were studied to compare the gelatinous fibres of root and stem wood. Species that possessed gelatinous fibres in root wood also possessed them in stem wood, but only two taxa showed the reverse condition. Gelatinous fibres did not exhibit an organ-dependent specificity in their transectional distribution. In roots, the gelatinous fibres generally differentiated immediately after initiation of secondary growth, whereas in most stems they differentiated considerably after the onset of secondary growth. The positive correlation detected previously between the distribution pattern, as well as the number of gelatinous fibres, and the eccentricity of the stem or root could not be verified. Even perfectly noneccentric roots and stems showed variations in the distribution pattern and number of gelatinous fibres. In roots, generally, all fibres were gelatinous, whereas in stems both gelatinous and normal fibres were present and showed different distributional patterns. All three types of gelatinous fibres (convolute, thick, and intermediate) recognised by earlier workers and based on the gelatinous layer were observed in this family. Gelatinous fibres of this family formed lignified, partially lignified, and nonlignified gelatinous layers. Differences were also noticed in the relative thickness of the gelatinous layer.