Ivy is an remarkably variable plant. Leaf size, shape and coloration differ tremendously among cultivars, most of which have been found as mutations rather than having been bred on purpose. Not only do cultivars vary, individual plants, depending on their level of maturity, can have leaves that bear almost no resemblance to others growing a few inches away.
Mature Ivy
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Dimorphism A difference in size, form, or color, between individuals of the same species, characterizing two distinct types. |
The variations in ivy are fascinating; not only the variety of colors and forms, but also the rather strange behavior when it matures. The ivy plants we grow have juvenile foliage, which can be quite different from that of mature specimens of the same species, a trait known as dimorphism. Most of the junipers on the market are dimorphic, for example, and the Eucalyptus so popular for dried arrangements is a juvenile leaf form from a dimorphic tree.
It takes more than just age for ivy to acquire mature foliage. It has to grow vertically until it can grow no farther - and be of a certain age. I have read fifty years, but some of the Hedera helix that I have growing up trees has reached this stage in less than half that time.
Once mature, ivy flowers in late summer or early fall and sets inconspicuous black, berry-like fruits which mature in spring of the following season. This scan is of a branch of mature leaves and flowers from one of the smaller leafed versions of H. helix. I have no clue to the cultivar name as it was started from a bit given me by my mother. The flowers aren't showy, but if you crane your neck up, you notice them.
I have seen mature ivy growing on a wall in England that made quite an impact. I didn't recognize it as ivy and had to ask what that marvelous vine was (felt a bit of a fool when the gardener said "ivy"). I've also seen photographs showing ivy flowers in bright yellow and huge bunches which could be extremely showy in the garden.
Another interesting trait is that the mature leaves change both size and shape. This scan shows a mature leaf on the right and immature leaves in the process of changing their shape on the left. The typical leaves are on the far left. In the center are intermediate forms. Note how the central section elongates and eventually the two bottom lobes disappear. The difference in size is considerable, too.
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