In general, they present "compitum", a region of the style where the stylar canals of the different carpels are united in a single cavity and in which the pollen tubes can change direction of growth from one carpel to another. The ovules are usually of axillary placentation. The pistil, finally, commonly terminates in a style and a stigma that is not decurrent. The fruit is dry and dehiscent, when it is a capsule it shows loculicidal dehiscence. Regarding the interaction between pollen and pistil, pentapetalous plants have a gametophytic incompatibility system based on the RNAase system. Another anatomical characteristic of Pentapetalae is the presence of a closed root apical meristem. From the phytochemical point of view, this group of plants present cyanogenesis —that is, they biosynthesize cyanogenetic glycosides that by hydrolysis originate cyanide— through the metabolic pathway of branched amino acids, such as leucine, isoleucine and valine. Diversity Dilleniales Dilleniales are recognized by their leaves with usually strong and parallel secondary veins that go straight to the teeth; being common the tertiary scalariform venation. The leaf lamina is usually rough. Also, the leaves tend to elongate when still rolled. The wood is usually vivid brown. The peduncles are jointed near the apex and persist after the flower falls off; the flowers are usually conspicuous, with ruffled petals and numerous stamens that are reflexed in the bud, usually having porous anthers. The fruits are small follicles containing seeds with aril, the calyx is persistent, sometimes acrescent, and the filaments are also persistent. Berberidopsidales Berberidopsidales is an order formally accepted only in the most recent phylogenetic classifications of angiosperms, comprising two small families, Aextoxicaceae and Berberidopsidaceae, which together include only three genera and four species distributed in Chile and eastern Australia. The distinctive characters of the order are largely related to its anatomy, such as the presence of crystals —especially drusen— in the leaves and petioles, the vascular bundles of the petiole form a ring and the stoma of the leaf epidermis are of a particular type called "cyclocytic". The androecium has stamens with rigid filament and the seeds present endotesta. The flowers of Berberidopsis corallina do not differ in sepals and petals, but exhibit a gradual transition from small outer tepals to larger, brightly colored inner tepals. The androcecium consists of a ring of stamens and there are three carpels with parietal placentation. In contrast, Aextoxicon has unisexual and pentamerous flowers.