Hydrangea arborescens L.

Hydrangea arborescens plant

Family - Hydrangeaceae

Stems - To +2m tall, glabrous, glaucous, suffrutescent, terete, with white pith, erect, multiple from the base, branching.

Leaves - Opposite, decussate, petiolate. Petioles to 15cm long, often with a purple tinge, glabrous to sparsely pubescent. Blades broadly ovate to orbicular, dentate, sparse strigose above, pubescent below, acute, deep green above, silvery-green below, +/-13cm in diameter.

Hydrangea arborescens leafPressed leaf.

Inflorescence - Terminal cyme. Branches of inflorescence fleshy, pubescent, Outermost flowers sterile, with large white bracts. Innermost flowers fertile. Pedicels to 3mm long on inner flowers.

Flowers - Fertile flowers - Petals 5, white, ovate, fugacious, glabrous, cupped, distinct, to 2mm long, 1mm broad. Stamens 10, erect to spreading. Filaments white, to 5mm long, glabrous. Anthers white, 2-lobed, 1mm broad. Styles 2, white, thickened, glabrous, -1mm long. Ovary partially inferior, 2-locular, with many ovules. Placentation axile. Hypanthium white, 1mm long, mostly glabrous. Outermost flowers - White bracts to +/-1cm in diameter, orbicular, pubescent, typically unequal.

Hydrangea arborescens bractsFalse flower of inflorescence.

Hydrangea arborescens flowersActual flowers, close-up.

Flowering - May - July.

Habitat - Rich wooded slopes, ravines, along streams, base of bluffs.

Origin - Native to U.S.

Other info. - This species can be found mainly in the Ozark region of Missouri. It prefers shaded low woods. The plant would do well in a shaded garden setting and should be cultivated more.
Steyermark breaks the species up into many different varieties and forms depending on leaf pubescence, leaf shape, and the presence or not of the sterile flowers. I won't go into these plants here as many of them are not valid.
"arborescens" means "becoming tree-like" since the plant gets woody with age.

Photographs taken near Stegal Mountain, Shannon County, MO., 6-21-03, and at Alley Spring, MO., 6-12-04.


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