All Ivies are evergreen, and they usually have stout, matte brown stalks, with glossy green leaves attached directly to the stems. Most Ivies are self-clinging climbers, which attach themselves to walls, fences and other plants by the use of aerial roots. They have two types of leaves: the juvenile leaves are palmately lobed, which means look a little like an outstretched hand: but the adult leaves - found on mature and flowering stems - are unlobed, and have a cordate (heart-shaped) base. This can lead to some confusion when identifying ivy growing out in the wild: as can the plant's habit of suddenly producing masses of tiny pom-pom flowers, followed by spherical bundles of tightly-packed, matte black fruits
Truth or Myth!
There are two main contemporary beliefs about Ivy: that it ruins houses, and that even if you cut it off at the base, the top will stay alive.
So does Ivy ruin houses? This belief stems from the days of soft lime mortar, when new stems could easily push themselves into the spaces between bricks or stones, then as the plant matured, the stems would thicken, and push the bricks or stones apart, so the walls would come tumbling down. Unless you have an old house built with lime mortar, this is far from likely to happen. Contemporary houses use much stronger cement and sand mortar that is much harder and, if kept in good condition, ivy can cling to it, but shouldn't destroy it. However, even with modern houses care should be taken not to let an ivy climb to the top of a wall and start pushing up the tiles of a roof, which can lead to significant water damage and rotting of roof timbers.
Single thickness garden walls can be at risk: they often have poorly applied mortar, and Ivy can find the tiniest gap, and can push its way into them. So it is not a good idea to allow it to grow unchecked over any outbuildings or walls. Fences are also very prone to damage by Ivy: the stems easily push their way between the slats, and can then, as they thicken, distort and force the panels apart.
That all said, on the plus side, research by English Heritage has shown that a thick coat of Ivy on a well-kept wall acts as a thermal store, keeping the wall cooler than a bare wall in summer, and warmer than a bare wall in winter. However, you would need to weigh against this slight gain the fact that ivy is cram full of bugs, insects, dust, dirt, creepy crawlies and the occasional nesting bird.
As far as cutting at the base goes, this is completely untrue: if you sever the stems at the base, the section above will eventually die, but there are two factors you need to know about. Firstly, the way ivy clings is by aerial roots, and these roots solidify at the death of the plant: they actually go rock-hard, and cling even tighter to the support. So don't cut the base and expect the upper part to fall down of its own accord, as it won't! The other issue is that those aerial roots, before they die, will use the last of the energy in the cut stem to convert themselves from anchorage into water-seeking, and if they can find their way through a wall and out the other side, into soil, or into a damp area, then the upper levels of the plant will indeed survive.
Actually, there is a third urban myth, that ivy growing up a tree will smother and harm it. This is not strictly true, as ivy is not a parasite, it does all its own photosynthesising and takes nothing from the tree other than support. However, it can add a considerable weight to a tree, which can cause damage and breakage to the branches: it also acts as a sail in the winter, at a time when a deciduous tree is expecting to be bare of branch and limb, and therefore can make a tree more prone to being blown over or damaged by high winds.
In addition, it creates a massive habitat for insects (and nesting birds), some of which are harmful to the tree: and finally, if the Ivy stems become wide and thick, they can smother the lenticels on the trunk of the tree, adversely affecting the tree's ability to respirate. For all these reasons, it is not a good idea to allow Ivy to colonise a tree: and in the garden, a thick coat of ivy at ground level, around shrubs and smaller trees, will deprive those plants of much water and nutrients.
So what about other plants called Ivy?
There are 77 plant records in our PlantFinder for Ivy, all within the genus Hedera: these start with our “Common” ivy, Hedera helix, which grows in abundance in the wild, but which has nearly 60 cultivars listed already. Then we have the rather similar-looking Hedera hibernica, which is excellent for quickly covering unsightly buildings: or, if you would like something a little different, Hedera pastuchovii which has interesting long leaves.
There are several Ivies which have presumably named after the region in which they were first found, including Canary Island Ivy, the common name of both Hedera algeriensis and Hedera canariensis; Himalayan Ivy, or Hedera nepalensis, and two types of Japanese Ivy: Hedera rhombea which sounds as though it should have rather angular leaves, and Hedera saggittifolia, which sounds rather like a star sign.
We also have five cultivars of the large-leaved Persian Ivy - Hedera colchica - most famous of which is 'Sulphur Heart' with brilliantly yellow-splotched leaves. These large-leaved Ivies are much less invasive than the more common ones, and can be used to great effect on trellis for screening.
When it comes to imposters, there are many plants with Ivy in their name, usually because the leaves are somewhat similar in shape to those of Hedera. Starting with the most obvious ones, we have Parthenocissus, whose various species are known as Boston ivy or American ivy, and which are famous (and popular) for their spectacular autumn colour.
Then there are several tender climbers, including Rhoicissus or Grape ivy; Cissus or Kangaroo vine, which is also - confusingly - called Grape ivy, and Peperomia fraseri or Ivy-leaf pepper. Other tender climbers include Epipremnum aureum which is known as Solomon Island's ivy, or even Devil's ivy, and Senecio macroglossus, another climber but this time with daisy-like flowers, which is known as German ivy, or Natal ivy.
Swedish ivy, or Plectranthus australis (why is it not called Australian Ivy? Who knows...), on the other hand, is not a climber at all, and doesn't look the least bit like any sort of Ivy, as it looks more like some kind of strawberry on steroids.
Nepeta × faassenii is a fairly ordinary Catmint, with no real grounds for calling it Ground ivy: it doesn't grow along the ground, and the leaves are nothing like those of Ivy. Likewise, Mexican ivy appears to be an utterly inappropriate common name for Cobaea scandens, better known as the Cup-and-saucer vine: but Mexico is where the plant comes from.
Another very non-ivy-like shrub is Leucothoe fontanesiana, which rejoices in the common names of Fetterbush, Dog-hobble, and Switch ivy. A slightly-more-than-cursory search of the internet did not reveal why it has these strange names: fetter and hobble usually mean “to tie up”, and a switch is the name for a slender whippy twig, used for discipline or to make horses, donkeys and goats go faster, which would seem to be two rather contradictory uses.
Then there is Schefflera, the Umbrella tree or Ivy tree, a tropical plant that, again, is somewhat mis-named, as the large exotic leaves are palmate, rather than Ivy-shaped: and it is more of a large shrub than a tree, if you were being picky.
Moving down radically in size, many of us are familiar with those summer conservatory standbys, the Ivy leaved Pelargonium, but even smaller are the pretty miniature snapdragon flowers of Cymbalaria muralis or Ivy-leaved toadflax, which grows as a weed in many gardens, particularly liking old stone walls. Would you consider those leaves to be ivy-shaped? Hmm, not really.
Rather similar-looking is Glechoma hederacea or Ground ivy, whose stems clamber and weave just like Cymbalaria: and similar in scale and habitat is that well known garden weed, Veronica hederifolia or ivy-leaved speedwell. Another delicate weed er, sorry, wildflower, is Wahlenbergia hederacea or ivy-leaved bellflower, whose pale blue bells can be found in southern England in July and August, in damp meadows. None of these have particularly ivy-shaped leaves, and none of them are evergreen!
Talking of weeds, we have some water plants, such as Lemna trisulca which is called Ivy-leaved duckweed, and which can be found floating below the surface of freshwater ditches and ponds, along with the moisture-loving Ranunculus hederaceus or Ivy-leaved crowfoot.
Moving indoors again, we have Chlorophytum comosum which is normally known as Spider plant, but apparently is also known as Spider ivy, despite being a house plant with no apparent resemblance to Ivy at all.
One rather unusual not-quite-Ivy is Fatshedera lizei or Tree ivy, which is a bizarre cross between the hardy garden shrub Fatsia, and a Hedera, resulting in a somewhat lax shrub which won't quite climb, won't quite stand up alone, but which has ivy-like leaves. Quite why anyone would bother to do such a thing, we don't know, but presumably it is popular with somebody, somewhere, as there are now several species, and apparently it is quite useful as a shade-tolerant indoor plant.
Then we have Orobanche hederae, or Ivy broomrape, which is not so named because it looks like Ivy, but for quite a different reason: it is one of a genus of parasitic plants, and is named after its specific host. These plants have pale, yellowish stems with snapdragon-like flowers, and are quite unable to photosynthesise for themselves: instead they insert root-like structures into a handy Ivy, and steal all the nutrients they need.
And finally, one of the oddest Ivies of all: Hedera erecta, which grows - as you can probably guess from the name - upright, instead of clinging to walls. It has no aerial roots at all, and is very well-behaved: the stems grow stiffly upright to a height of 3-4' (a metre or so) and then they slowly curve over under their own weight, before heading back upright again. This Ivy welcomes pruning, which just makes it branch, and become even more interesting in shape. Being evergreen, like all the other Ivies, it provides winter shape and colour, and can even be encouraged into forming a low hedge - with no threat to nearly trees, walls, or fences!