[2.20] Viola sect. Xylinosium 

Viola sect. Xylinosium W. Becker in Nat. Pflanzenfam., ed. 2 [Engler & Prantl], 21: 373. 1925.

—Lectotype (designated here): Viola arborescens L.

=Viola [sect. Nomimium; unranked] Fruticulosa Nyman, Consp. Fl. Eur. 1: 76. 1878, nom. inval. (Shenzhen Code Art. 32.1)

Description.—Perennial subshrubs. Axes not morphologically differentiated. All stems aerial, decumbent or ascendent. Stipules green, linear, with 0–2 basal, lateral, smaller segments. Lamina lanceolate, crenate or subentire, sessile or indistinctly petiolated. Bracteoles minute or caducous (0–2 mm). Corolla violet to whitish with a white throat or corolla bright yellow throughout. Spur stout or saccate, longer than calycine appendages. Style clavate, unmargined, beardless. Cleistogamous flowers not produced. Allopolyploid (CHAM + MELVIO). Secondary base chromosome number x’ = 26. ITS sequence of MELVIO type.

Diagnostic characters.—Subshrubs AND lamina lanceolate, remotely crenate, indistinctly petiolated AND base chromosome number x = 26.

Ploidy and accepted chromosome counts.—≥4x; 2n = 52 (V. arborescens, V. saxifraga).

Age.—Crown node age 5.6 (3.9–6.2) Ma; [28].

Included species.—3. Viola arborescens L., V. saxifraga Maire, V. scorpiuroides Coss.

Distribution.—Three disjunct species in the Mediterranean region (Figure 1): Viola saxifraga in the high Atlas, V. arborescens in the western Mediterranean, V. scorpiuroides in the southeastern Mediterranean.