Lacecap Describes the Lacy Flower Structure on Several Hydrangeas
Do you know that the wild types of hydrangeas are not mopheads, rather they are mostly lacecaps in their native forests? The unique structure of lacecap flowers is the way they attract pollinators and reproduce in the wild.
A Little Botany
Before we explain the lacecap flower, a few terms need to be defined. If you want textbook definitions, please consult your favorite botanical reference or the on-line Dictionary of Botany.
Inflorescence - A hydrangea flower is also known as a flower head or inflorescence, so I may use these words interchangeably. Then it gets a little more complicated because what we call a hydrangea flower is really a bunch of flowers held together on one head.
Floret - When a flower is complicated like that, each individual flower is called a "floret." A floret is one flower on an inflorescence. Many florets comprise a hydrangea flower.
Sepal - Here's the big surprise: hydrangeas don't have petals. What you see colored pink, blue, or white are called sepals and sepals are . . . modified leaves!
Lacecap Flower Structure
Lacecap hydrangeas flower heads are classified as corymbs.
Corinne Mallet defines a corymb as "An inflorescence composed of flowers [florets] which open at the same level, but whose peduncles [individual floret stems] are not all attached to the same point of the stem." Corinne wrote Hydrangeas Species & Cultivars and I find her definition the most straightforwardly pertaining to Hydrangeas.
In hydrangeas, corymbs are set up by nature to have two kinds of florets in the lacy flower head - fertile and sterile florets.
The showy sterile florets ring the edge of the flower head and so are also called ray florets, like the ray flowers of a sunflower. These sterile florets have large, showy sepals because it's their job is to attract pollinating insects to the inner fertile florets. There are only comparatively few of these showy florets needed to attract pollinators, but the fertile florets are in great quantity to ensure pollination.
Fertile florets are much smaller, but more numerous. The fertile florets don't have sepals because they don't need to be showy. It's the job of the fertile flowers to be pollinated, then make fruit/seeds and reproduce so the species lives on in the woods.
Same as their showier relatives, lacecap flowers come in the classic hydrangea colors of pink, blue, and white with variations and permutations similar to mopheads, such as double florets.
Like mopheads, lacecaps are subject to color change based on the pH of the soil.
Historic Lacecap Hydrangea Cultivars
Now you know lacecaps are the wild types and that mopheads are the quintessential garden variety. However, along with selecting mopheads, Japanese gardeners did select lacecaps for their gardens.
One of these are historic types, dating back over a hundred years is Veitchii - a famous and ancient white lacecap.
Mopheads Have Overshadowed Lacecaps
In our plant booth at the Penny McHenry Hydrangea Festival in Douglasville, Georgia, I was surprised to find people approaching our Irish Lace, Lady in Red, Veitchii, and White Wave lacecap hydrangeas with a sense of wonder. They had never seen a lacecap before!
It was fun for us to be a part of their plant journeys and to witness their delight in beholding and learning about lacecaps for the first time.
I was personally thrilled because lacecaps have long appealed to me. A modest collection of three white lacecaps were the only bigleaf hydrangeas I planted in my first small garden.
Lacecaps are not bodacious, rather they are refined and delicate-looking, having the appeal of a delicate objet d'art.
More Lacecap Hydrangea Cultivars are Coming
As breeders are developing new plants, they seem to be turning their attention to the lacecaps hydrangeas - finally!
Within the last decade breeders introduced Lady in Red, Irish Lace, and Twist-n-Shout, all with superior characteristics.
Lady in Red was introduced just after the turn of the 21st Century. Her flowers change colors from white at opening to pink or blue, then to dark pink. In autumn the Lady's foliage turns burgundy red. She has some H. serrata parentage in her ancestry.
The white lacecap Irish Lace blooms up and down the stem at each node, rather than only at the end of each stem like most other hydrangeas. Plus the flowers appear in both leaf axils at a node, not just one - it's like a doublefile viburnum that way. The resulting arch of flowers earned it the common name "garland hydrangea." Irish Lace inherited these node-flowering traits from Hydrangea angustipetala parentage.
In the pastel lacecap category we have Twist-n-Shout. The large lacecaps express themselves blue or pink, depending on pH. Twist-n-Shout is remontant, meaning it blooms twice - once in spring and again in autumn. This is the only remontant lacecap that I know of.
A new lacecap hydrangea with hot pink flower heads is turning human heads (not just getting the attention of insects). It's called Cherry Explosion and that's a great name for it. It will radiate color in your garden. A neat thing about this new one is that it seems to hold the dark pink very well in different pH levels. We have seen it purple once, but have not yet seen it in the blue iteration. When purple, it was also color saturated and quite compelling (follow a link to see a pic of the purple).