Frangula azorica V. Grubow is a Macaronesian flora medicinal plant, endemic from Azores islands and inscribed on the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species. This species, known as “sanguinho,” belongs to the family Rhamnaceae, the same as Frangula alnus Mill. and Frangula purshiana (DC.) J. G. Cooper, two widely used official laxative herbal medicines of the western Pharmacopoeias constituted by the dried barks of each species. Morphological and chemical studies on F. azorica dried bark are scarce although it is potentially recognized as a Portuguese laxative herbal medicine. Macroscopically, the bark occurs in quills or nearly flat pieces. A channeled external surface with transversely elongated lenticels is characteristic. When the outer phellem layer is removed, a bright purple inner phellem layer is disclosed. Light and electron microscopy observations revealed flattened phellem cells with slightly thickened walls, cortical parenchyma with secretory ducts and groups of sclereids, phloem with groups of fibers and sheaths of parenchymatous cells containing druses or more frequently prismatic crystals of calcium oxalate, and parenchymatous medullary rays one to three cells wide with spherical starch grains. Observation of these botanical characteristics must be included in quality monographs of F. azorica bark herbal medicine.

The purpose of the present study was to investigate the dormancy break and germination requirements of seeds from the rhamnaceous vine Berchemia scandens. The fleshy fruit contains a two-locular stone with an endocarp described as ‘bony, thickish’. Scarified and non-scarified stones increased by about 30–50% in mass during imbibition over a 24-h period. The endocarp of the stone does not completely enclose the seeds and a soft tissue region is present. This region is the primary area of water entrance to the seed, as shown by dye-tracking and by sealing it. Freshly matured and overwintered seeds of B. scandens germinated to low percentages at all temperatures during 2 weeks of incubation in light, and they germinated from moderate to high percentages during 12–14 weeks of incubation in light. While cold stratification had a relatively modest effect on the promotion of total germination across most temperatures assessed (if seeds were left for long enough), it had a somewhat stronger effect on germination rate. Cold-stratified seeds germinated equally well in light and darkness. The class of dormancy found in seeds of B. scandens would be physiological. The anatomy of the stones readily allows water imbibition, showing that seeds of B. scandens lack physical dormancy, an uncommon trait in Rhamnaceae.

Physical dormancy (PY) was identified in six genera representative of Australian Rhamnaceae and subsequently was broken, based on identification of key seed dormancy characteristics: (1) isolation and classification of embryo features; (2) imbibition experiments to determine the rate and amount of water uptake in seeds; and (3) determination of optimum temperature regimes for germination. All six species had relatively large spatulate embryos. Imbibition studies showed all species possessed PY (i.e. a water-impervious seed coat) that was broken by a hot-water treatment. Alleviation of PY resulted in high germination (<70%) at 7/18°C, temperatures similar to winter in south-west Western Australia. Germination was suppressed at higher temperatures and in the presence of light. The study adds information to our knowledge of seed dormancy in Australian Rhamnaceae, and highlights the benefits of understanding dormancy states in seeds prior to evaluating dormancy-release mechanisms on wild species used in restoration ecology and horticulture.