Oaks of the World

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 Quercus polymorpha
AuthorSchltdl. & Cham. 1830
Synonymsguatemalensis A.DC 1864 pro parte
petiolearis Benth. 1840
turbinata Liebm. 1854, nom. illeg. not Bl. 1825
varians Mart. & Gal. 1843
germana var. lemmonii Trel. 1924
polymorpha f. angustifolia C.H.Muller 1936
Local namesnet-leaf white oak ; mexican white oak ; Monterrey white oak ;
Range Mexico, on Atlantic slope (Chiapas, Hidalgo, Nuevo Leon, Oaxaca, Puebla, Queretaro, San Luis Potosi, Tamaulipas, Veracruz); Guatemala; SW Texas; 200-2450 m;
Growth habit 10-20 m tall; trunk to 50 cm wide;
Leaves 5-14 x 3-6 cm; coriaceous; oboval or oblong; apex obtuse, rounded or retuse, seldom acuminate, mucronate; base rounded or cordate; margin thickened, slightly revolute, somewhat cartilaginous, entire or with 2-5 pairs of short, mucronate teeth; green or glaucous, slightly lustrous, almost hairless above or with stellate hairs on midvein; paler, dull, glaucous beneath, hairless or sometimes loosely fascicled pubescent, and with rusty glandular hairs scattered, mainly along veins; 7-11 vein pairs, impressed above and prominent beneath; tertiary veins conspicuous beneath; epidermis glaucous, bloomy, papillose; petiole slender, yellowish, 1-3 cm long, glabrescent;
Flowers in March; staminate carkins 3-7 cm long, densely flowered, tomentose; pistillate flowers 1-2 on a pubescent peduncle less than 1 cm long;
Fruits

acorn 1-1.5 cm long, 0.8-1.2 cm in diameter, oblong; singly or paired on a 1-2 cm long peduncle; enclosed 1/2 by cup; cup velutinous, 1.2-1.5 cm in diameter, with strongly tuberculate triangular scales; cotyledons free; maturing in 1 year from October to December;

Bark, twigs and
buds

bark grey brown, scaly; twigs 2-3 mm wide, red brown, tomentose at first, becoming glabrous, with numerous lenticels; buds red brown, ovoid, pointed, 3-7 mm long; stipules pubescent, persistent around terminal buds, 10-13 mm long;
Hardiness zone, habitat not quite hardy : zone 7-8 (hardly withstands -16° C); all types of soil; cultivated in Spain, and in UK (at Kew);
Miscellaneous-- A. Camus : n° 210;
-- section Quercus; sub-section Polymorpha
-- discovered in 1992 only in the US Territory;
-- close to Q. splendens, which differs in having petioles 0.3-1 cm long, elliptic leaves usually entire, cotyledons connate, and habitat on Pacific slope of Mexico.
-- Q.guatemalensis A.DC : the type of this taxon has been described after the leaves, but the fruits are those of
Q.sapotifolia ...
Subspecies and
varieties
-- Q.juergensenii Liebm.1854 ( A. Camus : n° 211 )
from Mexico (Puebla), is a doubtful species, probably identical to Q.polymorpha, with petiole shorter and leaf base cuneate; for today's Mexican Authors (Susana Valencia-A., 2004), this species is not currently valid ; it may be a hybrid, or a morphological variety...
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