Fragment of the bark showing dispersal of medullary rays observed at 400x with Acidified Chloral Hydrate Glycerol Solution.
Source: Elan M. Sudberg, Alkemist Laboratories^[1]

Bark fiber showing calcium oxalate prisms spaced by medullary rays observed at 400x with Acidified Chloral Hydrate Glycerol Solution.
Source: Elan M. Sudberg, Alkemist Laboratories^[2]

Handroanthus impetiginosus HPTLC ID - 10% Ethanolic H2SO4 ->115° C 15 min -> UV 365 nm

Pau D’Arco (bark) (Handroanthus impetiginosus)

Lane Assignments Lanes, from left to right (Track, Volume, Sample):

1. 3 μL Handroanthus impetiginosus-1 (bark)
2. 3 μL Handroanthus impetiginosus-2 (bark)
3. 3 μL Handroanthus impetiginosus-3 (bark)
4. 3 μL Handroanthus impetiginosus-4 (bark)
5. 3 μL Handroanthus impetiginosus-4 (bark)
6. 3 μL Handroanthus impetiginosus-5 (bark)
7. 3 μL Handroanthus impetiginosus-6 (bark)
8. 1 μL Artemisinin ~0.1% in CH3OH

Reference materials used here have been authenticated by macroscopic, microscopic &/or TLC studies according to the reference source cited below held at Alkemists Laboratories, Costa Mesa, CA. 

Stationary Phase Silica gel 60, F254, 10 x 10 cm HPTLC plates 

Mobile Phase toluene: ethyl acetate: formic acid [7.5/2.5/0.5] 

Sample Preparation Method 0.3 g + 3 ml CH3OH sonicated + heated @ 50° C ~ 1 hr. 

Detection Method 10% Ethanolic H2SO4 ->115° C 15 min -> UV 365 nm 

Reference see Plant Drug Analysis, Wagner, H., 1996

Source: Elan M. Sudberg, Alkemist Laboratories ^[3]