1. Phytolacca root (Phytolacca americana, L.). 2. Squills (Urginea maritima [L.] Baker). 3. Hydrangea root (Hydrangea arborescens, L.). 4. Convallaria (Convallaria majalis, L.). 5. Carthagean ipecac (Cephælis acuminata Karst.) 6. Bundle of raphides from false unicorn root.
A. Bundle surrounded with mucilage. B. Mucilage expanded and partially dissolved. C. Bundle free of mucilage.
PLATE 80
Rosette Crystals
1. Frangula bark (Rhamnus frangula, L.).
2. White oak bark (Quercus alba, L.).
3. Spikenard root (Aralia racemosa, L.).
4. Wahoo stem bark (Euonymus atropurpureus, Jacq.).
5. Wahoo root bark (Euonymus atropurpureus, Jacq.).
6. Rhubarb (Rheum officinale, Baill.).
The prisms forming the rosette crystals, like all prisms, decompose white light, with the result that rosette crystals frequently appear variously colored. Rhubarb crystals, for instance, are blue or violet. Most of the smaller rosette crystals, however, appear grayish white with a darker-colored centre.
Rosette crystals occur in parenchyma cells (Plate 81, Fig. 4) and in medullary rays (Plate 81, Fig. 3).
SOLITARY CRYSTALS
Solitary crystals are the most variable of all the forms of calcium oxalate. They usually occur in crystal cells associated with bast fibres and stone cells, less frequently in stone cells (Plate 33, Fig. 2). There are many different and characteristic forms of prisms. The more common are:
1. Rectangular:
A. Parallelepipeds.
B. Cubes.
2. Polyhedrons:
A. Irregular polyhedrons.
I. Flat bases.
(a) Non-notched.
(b) Notched.
II. Tapering bases.
B. Octohedrons.
The crystals occurring in Batavia cinnamon and henbane leaves are parallelopipeds (Plate 82, Figs. 1 and 2).