Macroscopic— Bark pieces consist of long fragments of variable dimensions, from only a few cm to 1 m long with a thickness varying from a few mm to 1–2 cm. The color is brown, more or less dark on the external surface; light brown to red-brown on the internal surface. The external part of the bark presents a very dark and fissured rhytidome that in the samples of old trees is fragmented in more or less square plaques of about 1 to 5 cm. The thickness varies from 1 mm in young plants or branches to 5–8 mm in old plants. The outer surface may also be covered with whitish lichens or thin filamentous moss. The internal bark, under the rhytidome, is clearer and has a more reddish coloration, with a long fibrous break, from reddish to light brown and dark brown in color, often presenting concentric stratification cracks. The internal surface is clearer and presents small wrinkles.

Microscopic— The transverse section of the bark presents a suberized bed having a thickness depending on the age of the plant, consisting of multiple layers of small, square cells with the walls of moderate thickness. It presents a cortical parenchyma of more or less round cells, with a few apparent formations of very thin-walled sclereids, definitely sharp. Often, in the parenchyma, there are groups of cells containing oxalate druses; a few bigger cells with highly thickened walls can also be observed. It shows a liber with phloem zones and presenting medulary rays. The phloemical portions contain groups of fibrous cells with highly thickened walls as well as phloemical and parenchymal elements, sometimes containing druses of oxalate. The medulary rays are of conical shape, larger on the external surface and thinner on the internal side; they can also contain druses of oxalate.

Adsorbent: 0.25-mm layer of chromatographic silica gel mixture.

Test solution— Transfer about 10 g of the powdered plant material to a soxhlet apparatus. Extract with 150 mL of methylene chloride for 4 hours. Evaporate the extract under vacuum to dryness. Dissolve the residue with 10 mL of methylene chloride. Apply 10 µL to the plate.

Standard solution 1— Prepare a solution of USP Pygeum Extract RS in chloroform having a concentration of about 10 mg per mL.

Standard solution 2— Prepare a solution of USP -Sitosterol RS in chloroform having a concentration of about 1 mg per mL.

Developing solvent system: methylene chloride in a saturated chamber.

Spray reagent— Prepare a solution of sulfuric acid and water (1:1).

Procedure— Develop the chromatogram to a length of not less than 15 cm, and dry the plate in a current of air. Spray the plate with Spray reagent, and heat the plate at 100 for 10 minutes. Examine the plate under white light: the chromatogram obtained with the Test solution shows one red-violet zone turning to grayish-brown near the origin that corresponds in color and RF value to that in the chromatogram of Standard solution 1; one red-violet zone turning to grayish-brown at an RF about 0.08, corresponding in color and RF value to that in the chromatogram of Standard solution 2; above these spots a grayish-brown zone may be present, corresponding in color and RF value to that in the chromatogram of Standard solution 1. Other colored zones of varying intensities may be observed in the chromatogram of the Test solution.