VII. Lundia clade

TAXONOMIC INFORMATION. — This clade contains a single genus, Lundia, with multiple of four phloem wedges in transversal section.

TOTAL NUMBER OF SPECIES IN THIS CLADE. — 13 species (Lohmann & Taylor 2014; Kaehler & Lohmann 2021a).

STUDIED SPECIES. — Five species, Lundia longa (Vahl) DC., L. damazioi C.DC., L. densiflora DC., L. virginalis DC., and L. nitidula DC.

Regular phloem

Thin fiber bands (Fig. 10H) and assemblages present.

Variant phloem

General configuration. Fibrous (Fig. 10G, I), with axial elements in a tangential to diagonal arrangement (Fig. 10G, I).

Sieve-tube elements. As seen in transverse section, each sieve element is associated with one companion cell, rarely two (Fig. 10I). The sieve elements may be solitary to multiples of 2-3 (Fig. 10I). Narrower sieve elements with just one companion cell may be found in a parenchyma band present in all species studied. As seen in longitudinal section, the sieve elements are long (over 1 mm) and their end walls are inclined, bearing sieve plates with 12-15 sieve areas.

Axial parenchyma. The phloem parenchyma is sieve-tube-centric to sieve-tube-centric incomplete, therefore surrounding or partially surrounding the groups of sieve elements (Fig. 10I). Furthermore, a parenchyma band composed of 2-3 cells of phloem parenchyma is associated with sieve elements of narrower diameter. The phloem parenchyma tends to form radial rows of 4-6 cells in some places.

Fibers. Fibers form the background tissue where all other cells are embedded (Fig. 10G, I).

Rays. The limiting rays are only lignified to the xylem face (10G). The wedge rays have randomly alternating portions lignified and non-lignified.

Crystals. Acicular crystals are present in the phloem and ray parenchyma across the entire phloem wedge (absent in Lundia longa).

Periderm

A single periderm formed. The phellem is non-stratified, composed of evenly thin-walled cells in Lundia corymbifera and L. virginalis . The phellem is stratified in Lundia longa, with alternating thin and thick-walled cells.The phelloderm is thick, with over three layers of cells, non-stratified (Table 2). The lenticels are non-stratified, with unlignified filling tissue (Table 2).