In a recent stretch, over half the questions I received came from people trying to unravel the mysteries of hydrangeas. Although there is a lot that I don't know, researching, and thinking about those questions emboldened me to tackle hydrangeas in an article.

On second thought, that can't be done. Glancing at two catalogs I frequently use, I see that one lists 35 different hydrangeas and the other has 71.

To add to the confusion, those numbers cover as many as five species of hydrangeas all with different looks and/or different habits. Also in play is that usually some of the florets are sterile and some are fertile. So here comes a two-week effort.

To unravel the species confusion, let's start with our native hydrangea, Hydrangea arborescens. There are several cultivars, with Annabelle the most common. If you need to push a hydrangea into a lot of shade, this is the answer.

It gets a large snowball flower that starts green and gradually turns pure white. A disappointed owner recently described its early bloom stages as a hydrangea whose flowers never open. While not the showiest, it has its place in the shady landscape. I like it and find it interesting. The other hydrangeas want no more than dappled shade.

The second species is the one we usually envision when we think about hydrangeas. That one is big leafed hydrangeas or using the Latin is Hydrangea macrophylla. This one includes the common lacecap and mophead forms. Again we get a balance of fertile and sterile florets. The showy ones are sterile and the ones that appear unopened or underdeveloped are fertile.

Recently I am seeing another species, called Hydrangea serrata. This one appears quite similar to the mycrophylla in bloom but with possibly smaller leaves and a bit of color in the leaves both in the fall and the growing season. Išve only seen one or two cultivars of this one to date.

When I was about five, I remember climbing a giant snowball tree that grandmother had planted by the front porch. In reality I guess 10 to 15 feet isn't a giant to an adult. It was one of the Hydrangea paniculatas. This group sports large oblong white flowers that fade to pink and then to light tan. They can be trained to be a large multi-stemmed shrub or a small tree.

To many people the most desirable hydrangea is the oakleaf or Hydrangea quercifolia. You guessed- it the leaves look like large oak leaves. The flowers again are oblong and have the same color sequence as the paniculatas.

This one stands out because it has multi-season interest. You start with the spring foliage, and then the bloom, followed by good purple fall foliage, and bark that is cinnamon-colored and very hairy when young and exfoliates as it ages. This is one of my favorite shrubs for four-season interest.

That runs the gamut of common possibilities if we allow for a multitude of cultivars in each group and extensive hybridization. Also, there has been a rash of recent introductions from the mountains of eastern Asia in an effort to increase hardiness. We will continue next week with culture and growing tips to avoid some frequently encountered problems.