XI. Callichamys clade

TAXONOMIC INFORMATION. — This clade contains a single genus, Callichlamys Miq., with four phloem wedges in transversal section.

TOTAL NUMBER OF SPECIES IN THIS CLADE. — One species (Lohmann & Taylor 2014).

STUDIED SPECIES. — One, Callichlamys latifolia (Rich.) K.Schum.

Regular phloem

Thin fiber bands, assemblages present.

Variant phloem

General configuration. Non-fibrous (Fig. 13E), with approximately 9-18 rows of sieve tubes and phloem parenchyma cells between fiber bands. The axial elements show a diffuse arrangement (Fig. 13E).

Sieve-tube elements. As seen in transverse section, each sieve element is associated with one companion cell, seldom two. Sieve tubes of two distinct diameters occur together and are predominantly solitary, occasionally in radial or tangential multiples of 2-3. As seen in longitudinal section, the sieve elements are short (<1 mm) with inclined end walls, bearing sieve plates with 6-7 sieve areas (Fig. 13F).

Axial parenchyma. The phloem parenchyma forms a matrix where sieve elements and fiber bands are embedded (Fig. 13E), with cells that may be as wide as the sieve tubes. Sometimes radial rows of 3-4 cells of phloem parenchyma may be found between sieve elements. A crystalliferous parenchyma surrounds the fiber bands.

Fibers. The fiber bands in Calliclamys are composed of 3-4 cell rows (Fig. 13E).

Rays. The limiting rays are lignified only to the xylem face. The wedge rays are non-lignified, even when crossing the fiber bands (Fig. 13E).

Crystals. Acicular crystals are predominate in the crystalliferous parenchyma, but can be also found in other cells of the phloem and ray parenchyma.

Periderm

A single periderm formed. The phellem is non-stratified, and evenly thin-walled (Table 2). The phelloderm is thick, with over three layers of cells, stratified. Lenticels are non-stratified, with unlignified filling cells (Table 2).