VI. Pachyptera clade

TAXONOMIC INFORMATION. — This clade contains a single genus, Pachyptera, with four phloem wedges in transversal section. Pachyptera currently includes species from three previously recognized genera (see Fischer et al. 2004; Table 1), Leucocalantha Barb. Rodr., Mansoa, and Pachyptera .

TOTAL NUMBER OF SPECIES IN THIS CLADE. — Five species (Francisco & Lohmann 2018).

STUDIED SPECIES. — Two species, Pachyptera aromatica (Barb. Rodr.) L.G. Lohmann, and P. kerere (Aubl.) Sandwith.

Regular phloem

Thin to thick fiber bands (Fig. 10D), assemblages absent.

Variant phloem

General configuration. Non-fibrous (Fig. 10D), with approximately 8-18 rows of sieve tubes and phloem parenchyma cells between fiber bands (Fig. 10E). Axial elements present a diffuse to radial arrangement (Fig. 10E, F).

Sieve-tube elements. As seen in transverse section, each sieve element is associated with one companion cell (Fig. 10F). The sieve elements occur either solitary or in multiples (Fig. 10F), sometimes in short groups of 2-3 cells either in tangential or radial arrangement (Fig. 10F). As seen in transverse section, the sieve elements are thinner than 1 mm and their end walls are inclined, bearing compound sieve plates with 6-7 sieve areas.

Axial parenchyma. The phloem parenchyma intermingles all other cells (Fig. 10E, F). Crystalliferous parenchyma is, moreover, found surrounding the fiber bands.

Fibers. Fiber bands are present, composed by 2-4 rows of cells (Fig. 10E).

Rays. The limiting rays are lignified only to the xylem face (Fig. 10E). The wedge rays are non-lignified, except when crossing the fiber bands.

Crystals. Acicular crystals are present in the phloem and ray parenchyma. The crystalliferous parenchyma bears prismatic crystals.

Periderm

A single periderm formed. The phellem is non-stratified, composed of evenly thick-walled cells. The phelloderm is thick, with more than three cell layers, non-stratified (Table 2).