In a broad sense, there are two types of gardens commonly found in home landscapes. One is called a “collection garden” which is the type grown by people who are dedicated to one genus or category of plant.
For instance, there are said to be over 60,000 named cultivars of daylilies (Hemerocallis). There are over 8,000 named cultivars of Hosta. For each of these and other species such as iris (Iris), peonies (Paeonia) or roses (Rosa) with large numbers, there are gardeners whose primary goal is to accumulate as many specimens as they can. These gardens tend to prominently display all the most recent, “cutting edge” cultivars in addition to the old classics. Often there are few, if any, other species of plants included in collection gardens.