Flora of North America species comparison

Myoporum laetum is commonly cultivated in coastal areas of California. Although first collected outside of cultivation in 1949, it was not recognized as an introduced element of local and regional floras until the 1970s. It has naturalized mostly in southern California to San Luis Obispo County with some populations north along the coast to the San Francisco Bay area.

Myoporum insulare R. Brown, also cultivated in California, is similar to M. laetum, and some reports of M. laetum are possibly M. insulare. Myoporum insulare has leaves that are lighter green when young, and the translucent glands of the mature leaves are less conspicuous. The flowers are slightly smaller with anthers that are only slightly exserted from the tubes, and the fruits are smaller and globular.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Genera ca. 60, species ca. 1700 (9 genera, 45 species in the flora).

As noted in the introduction to this volume, the authors follow a narrow circumscription of Scrophulariaceae. Molecular studies (especially R. G. Olmstead et al. 2001 and B. Oxelman et al. 2005) have shown that some of the taxa commonly included in earlier treatments of Scrophulariaceae are better placed elsewhere, particularly in Orobanchaceae (hemiparasitic members, for example, Rhinantheae Lamarck & de Candolle) and Plantaginaceae (for example, Penstemon). Oxelman et al. and D. C. Tank et al. (2006) both recognized eight tribes in their analyses of the Scrophulariaceae. Five of the eight, Buddlejeae Bartling (Buddleja, Emorya), Leucophylleae Miers (Capraria, Leucophyllum), Limoselleae Dumortier (Limosella), Myoporeae Reichenbach (Bontia, Myoporum), and Scrophularieae Dumortier (Scrophularia, Verbascum), are represented in the flora area.

Inclusion of Myoporaceae (three or four genera and 125 species, in the sense of A. Cronquist 1981) is warranted based on its close similarity to Leucophylleae. Morphological similarities have led workers either to propose transferring Leucophylleae from Scrophulariaceae to Myoporaceae (C. J. Niezgoda and A. S. Tomb 1975) or to question the validity of recognizing Myoporaceae as distinct from Scrophulariaceae (J. Henrickson and L. D. Flyr 1985). R. G. Olmstead et al. (2001) confirmed this closeness in their molecular survey, with Leucophyllum and Myoporum clustering together and forming a clade sister to Buddlejaceae; Leucophylleae and Myoporeae also clustered together in the studies by B. Oxelman et al. (2005) and E. Gándara and V. Sosa (2013).

Members of Buddlejaceae (10 genera, ca. 150 species, in the sense of A. Cronquist 1981) often have been included in Loganiaceae (G. K. Rogers 1986) or treated as a separate family. Cronquist noted that the four-lobed corolla may be the primitive condition for the Scrophulariales and that Buddlejaceae is clearly not primitive. B. Oxelman et al. (1999) showed that Buddlejaceae is monophyletic; R. G. Olmstead et al. (2001) and Oxelman et al. (2005) both found that Buddleja clustered within Scrophulariaceae in the strict sense; that interpretation is followed here. J. H. Chau et al. (2017) found that Buddlejeae is monophyletic.

(Discussion copyrighted by Flora of North America; reprinted with permission.)