Family: Hydrangeaceae
Species: Hydrangea spp. L.
Common name: Hydrangea, Hortensia
Etymology
The name comes from the ancient Greek hydōr (“water”) and angos (“vase”), thus meaning “vase of water,” referencing the cup-shaped fruits reminiscent of small water vessels.
Description
There are numerous species and varieties of hydrangeas, making this genus one of the largest and most widespread shrubs after roses. Generally, they are deciduous shrubs identifiable by their flowering, comprised of many small or large blooms gathered in inflorescences. The overall shape of these inflorescences can be spherical, semi-spherical, conical, or more flattened, featuring sparse or dense umbels. Flower colours range from pure white to deep blue, including multiple shades of red, pink, and purple. Notably, the flower colour can vary based on soil pH: for instance, blue flowers display deep colour in acidic soil, yet turn pink in alkaline or neutral soil.
Hydrangea branches are robust—usually upright but curved in older varieties. Leaves are opposite, with an oval or elliptical blade featuring a serrated edge and pointed tip (or sometimes lobed). They have a substantial, bright green surface, sometimes shiny or matte, and specific cultivars develop red-brown hues in autumn.
Their persistent inflorescences (blooming from May to October) can be:
Globose: Composed only of sterile, bract-bearing flowers,
Flat/Slightly Rounded: Consisting of tiny fertile flowers surrounded by showy, sterile bracts,
Paniculate: Arranged in panicles.
Habitat
Most hydrangea species originate from Asia (China, Japan) or South America.
Properties and Uses
They are prized for ornamental purposes, adding charm and colour to parks and gardens.
Notes and Curiosities
Present in European gardens since the late 18th century, hydrangeas lend a romantic touch to green spaces. The genus offers numerous varieties and species emphasizing differing structures, forms, and foliage. Hybridisers often focus on traits such as the ability to rebloom, the colour of the inflorescence, and the size or shape of both the entire inflorescence and individual flowers (which can be double, triple, pointed, or fringed).
Within the Heller garden, hydrangeas contribute lively elegance among flowerbeds and pathways. Notable cultivars include:
H. paniculata
Origin: China
Inflorescence: Panicles (conical, drooping)
Leaves: Ternate, oval, light green
Flowers: Made up of fertile blooms, from which sterile flowers emerge with narrow white bracts finely incised at the edges
Blooming: Mid-summer
H. quercifolia
Origin: North America
Leaves: Deeply lobed, reminiscent of oak leaves; dark green turning red in autumn
Inflorescence: Small and conical, bearing sterile bracts with wavy edges, initially pale green before turning white
H. macrophylla
Origin: Japan (most commonly grown species)
Growth: Bushes typically form a symmetrical, rounded shape
Inflorescence: Globose or flat (pink, white, or blue), blooming from late spring to autumn
Preferred Conditions: Semi-shade
H. involucrata
Leaves: Velvety, dusty grey foliage
Buds: Surrounded by bracts with flat, irregular-ring inflorescences
Colour Change: Does not shift colour based on soil acidity
H. aspera
Leaves: Dark, thick, and velvety; among the largest in the genus
Stems: Vigorous and covered with bristly hairs
Inflorescence: Rounded, very open clusters featuring sterile white-pink flowers and fertile violet flowers.