Acer opalus       6451

This is a deciduous tree to 28m in the wild. The bark is grey, turning pale brown to orange grey and broadly plated, sometimes flaking with age. The branchlets are stout, glabrous or tomentose, reddish-brown. The buds are ovoid, acute tipped, with many pairs of imbricate scales, brown.

The leaves are chartaceous to subcoriaceous, broadly pentagonal in outline. The base is cordate, (3-) 5-lobed, 7-12 x 8-16cm, lobes shallow, ovate, lateral lobes spreading, basal lobes smaller. The apex is acute to acuminate, margins entire to remotely serrate, upper surface mid to dark green. The lower surface is paler, pubescent or not, often along veins but soon glabrous, or persistently villose. The petiole is 7-18cm long, green or red, faintly grooved and broadening towards the base. The autumn colors are yellow to brown.

The inflorescence is terminal, umbellate, peduncle and pedicels pubescent at first, pendulous, 6-16-flowered, 8-15cm long. The flowers are yellow, 5-merous, sepals ovate, 0.6cm long. The petals are narrow-oblong, 0.5cm long. There are 10-12 stamens, inserted inside the nectar disc. The samaras are to 2.5-5cm long, wings spreading variously. The nutlets are rounded.

References
- Jean Louis Helardot. Acer opalus
- Trees and Shrubs Online, International Dendrology Society. Acer opalus

- A systematic study of the genus Acer, Ken Ogata. 1967. Address
- Acer L. and Dipteronia Oliv. (Sapindaceae) Vegetative Key to species In cultivation, Jan De Langhe and Dan Crowley. 2018. Address
- eFloras. eFloras.org Vol. 2 pag. 100167. Acer
- Flora iberica, Santiago Castroviejo. 2010 Vol. 9 pag. 77-93. ISBN
- Maples of the World, D.M. van Gelderen P.C. de Jong H.J. Oterdoom. 1994. ISBN
- The Conservation Assessment of Aceraceae in Thailand, Nanthawan Suphuntee, Voradol Chamchumroon, Sommanussa Saengrit, Sukhonthip Sirimongkol. 2013. Address
- Hommes et Plantes. Vol. 67 pag. 24-29. Address

Indigenous plant
Biological type: tree
Frost resistance: 5ºF
Leaf color: dark green
Estimated lifespan: ± 255 years
IUCN Red List of threatened species status: Least Concern
Indexed Sensitive to the insect Popillia japonica The Regional Directorate for Food, Agriculture and Forestry.
Indexed Susceptible to the bacteria Xylella fastidiosa The Regional Directorate for Food, Agriculture and Forestry.
Indexed Sensitive to the insect Anoplophora glabripennis The Regional Directorate for Food, Agriculture and Forestry.

Specifications for the Mediterranean basin
Adult size (h x w): 39,3ft x 29,5ft
Sun exposure: part sun (Sun hours: >3h <6h
Foliage: deciduous
Growth: average

Specific information for our garden
Planting substrate: 30%Compost+30%Coco+40%Sand
Plant watering: 3x a week pH 5.5
Logical sequence of containers for: Oaks; 2L forestry pot, 6L container, 55L container, 110L container, 240L container
Propagation is done by cuttings

Ecology in its country of origin
Rainfall: 800-1600mm
Gravelly soil: a little
Sandy soil: a little

SPRING Keep in refrigerator at 39°F in dry condition. Soak the seeds in ambient water for 12h. Keep in refrigerator at 39°F for 12 weeks in humid substrat. Sow the seeds at 2mm depth in the Well Drained Seed Sowing Mix and pouwder with 2mm Vermiculite between 64-72°F. During germination keep the substrate moist and in daylight. The seeds germinate in 2-4 weeks.
The viability of the seeds, kept under good conditions, is one year.

Germination references
- Effect of different seed treatments on dormancy breaking and germination of Acer capillipes Maxim., Markovic, Marija and Grbic, Mihailo and Skocajic, Dragana and Djukic, Matilda and Bojovic, Danijela. 2019 pag. . ResearchGate
- Seed propagation of mediterranean trees and shrubs, Piotto and A. Di Noi. 2003. Link
- Seeds: Ecology, Biogeography, and, Evolution of Dormancy and Germination, Baskin, Carol and Baskin, J.M. 2014 pag. 1-1586. DOI

Germination references for the genus
- USDA Forest Service's Woody Plant Seed Manual, John K. Francis and Craig D.Whitesell. 2008. Address