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FNA | Family List | FNA Vol. 12 | Viscaceae

7. Phoradendron villosum (Nuttall) Nuttall ex Engelmann, Boston J. Nat. Hist. 6: 212. 1850.

Pacific or oak mistletoe Pacific or oak mistletoe

Viscum villosum Nuttall in J. Torrey and A. Gray, Fl. N. Amer. 1: 654. 1840; Phoradendron flavens Grisebach var. villosum (Nuttall) Engelmann

Subshrubs, erect, to 1 dm diam., dioecious. Stems green or olive green, grayish from pubescence, hairy, hairs stellate, becoming hirtellous to glabrate; internodes terete, 1.5–3.8 × 1–3 mm. Leaves green or olive green, grayish from pubescence, stellate-hairy; blade obovate-elliptic to orbiculate, 13–45 × 9–22 mm, thin to thick and fleshy, base subtruncate to acute, apex rounded to acute; basal phyllotaxy transverse. Staminate inflorescences 10–80 mm, stellate-hairy; peduncle with 1 internode, 2–4 mm; fertile internodes 2–5, each (14–)26(–44)-flowered, triseriate, becoming irregular, flowers 2–7 per column. Pistillate inflorescences 10–80 mm, stellate-hairy; peduncle with 1 internode, 2–4 mm; fertile internodes 2–3, each (6–)11(–24)-flowered, triseriate, flowers 1–4 per column. Flowers: petals 3–4, 1 mm. Berries white to pink, oblong to globose, 3 × 3 mm, puberulent below petals.

Subspecies 3 (2 in the flora): w, sw, sc United States, n Mexico.

Phoradendron villosum was treated by J. Kuijt (2003) as a synonym of P. serotinum subsp. tomentosum (= P. leucarpum in this treatment), but P. villosum has a different, non-overlapping flowering time, shorter stem internodes, and hairy berries. In addition, P. villosum averages fewer pistillate inflorescence fertile internodes than P. leucarpum. Molecular studies by V. E. T. M. Ashworth (2000, 2000b) showed that P. villosum did not form part of the strongly supported P. leucarpum clade. For these reasons, they are here considered distinct species, as was done by D. Wiens (1964).

Subspecies flavum (I. M. Johnston) Wiens, distinguished by its yellow leaf hairs, is found in Coahuila and Durango, Mexico.


1 Hairs on young stems, leaf blades, and inflorescences of one type, uniformly distributed and of similar lengths; pistillate inflorescence internodes each (7–)12(–24)-flowered; California, Oregon.   7a Phoradendron villosum subsp. villosum
+ Hairs on young stems, leaf blades, and inflorescences of two types, some in dense clusters, relatively longer, others uniformly distributed, relatively shorter; pistillate inflorescence internodes each (6–)8(–12)-flowered; Arizona, New Mexico, Texas.   7b Phoradendron villosum subsp. coryae

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