Some think Forsythia is the one and only yellow blooming shrub that heralds the beginning of spring. I've learned that "blooming early on still bare branches" is not such a rare feat for a woody plant. Winterhazels also perform this lovely magic. Please allow me to introduce them to you.
The genus Corylopsis is native to east Asia. A couple dozen species of deciduous shrubs there give us several choices in cultivation for our landscapes in temperate America. Blooms on winterhazel are a pale to golden yellow. The flowers occur in hanging clusters of layered bloom. They dangle from the bush's bare stems, and dance in the very earliest of the spring breezes. Winterhazels work well in shrub borders, and are at home and lovely in the woodland setting. I personally think their gentler yellow color is easier on the eyes and more "natural" looking than that of the common Forsythia. Winterhazels belong to an extended family of woody plants of outstanding cold-weather interest, the Hamamelidiceae (I love that word.) They are kissing cousins of witch hazels and Fothergilla. Corylopsis make excellent candidates for the garden, preferring a partly shaded location in rich, moist soil. Use winterhazel in full sun too, and less than perfect soil conditions, and it will perform well. There's not a lot of variety in the garden winterhazel; they are all generally yellow, early blooming and somewhat fragrant. Species and cultivars allow some attempt at catering to your preferences.
For the "most floriferous":
Michael Dirr says, in his Encyclopedia of Trees and Shrubs, that spike winterhazel (C. spicata) seems the "best behaved and most floriferous" of the winterhazels. Spike winterhazel may be the most well known of the group, being the species first propagated for Western landscape use.
For the neatest in habit:
Buttercup winterhazel, Corylopsis pauciflora, is admired for its generally (though not guaranteed) smaller size, its tidy growth habit and flowers of a lovely yellow. It's also praised for its fragrance. Don't be concerned over the species name that implies a lack (paucity) of bloom. Though there are fewer flowers in each cluster, the dense clusters and open blooms still make for a lovely show. The picture at below shows gorgeous buttercup winterhazels against the snow at Longwood Gardens (how's that for paucifloriferousness?).
For the largest bush:
Chinese winterhazel, Corylopsis sinensis, easily matures to ten to fifteen feet overall. Like all winterhazels, it clothes itself in dangling flower clusters in the days between winter and spring. More technical sources or suppliers may refer to it as Corylopsis sinensis var calvescens. And to further boggle your mind, there is a forma veitchiana, Veitch's winterhazel, which has been selected to grow in a more upright vaselike shape. Please don't think I'm hoping to dazzle you with Latin names; I simply feel they must be mentioned to help prevent confusion when shoppping for these shrubs.
As you might suspect from its name, fragrant winterhazel aka Corylopsis glabrescens, has a reputation for sweet perfume. Fragrant winterhazel is a large shrub, tending to a wide spreading form of eight feet or more. Vendors may offer an improved variety, gotoana. Gotoana is considered more garden worthy than the species, and will grow to a similar mature size and shape.
Winterhazel in summer and fall
Given a good, or even halfway respectable, planting spot, winterhazels do not require further care. Winterhazels prefer a moist, acidic soil, a partly shaded location, and perhaps shelter from wind. These conditions help ensure the best show from a winterhazel. They are cold hardy roughly to zones 5 or 6 and do well to zone 8 or 9 (sources vary.) If you garden on the cold end of that spectrum, look towards the fragrant (C. glabrescens) or spike (C. spicata) for the slightly hardier choices of the group. A properly sited winterhazel will grow to fill its spot and not need annual shearing. If needed, pruning is best done in spring soon after the blooms fall. If you are familiar with witch hazel or fothergilla, you'll see the similarity in the leaf shape on winterhazel. After or near the end of the bloom period, winterhazel produces its pleated and toothed, oval, leaves. Buttercup winterhazel's leaves are edged in red as they appear. Spike winterhazel offers up variety 'Ogon' ('Golden Spring') with leaves emerging in a yellow green, and 'Spring Purple' , graced with new leaves of dark purplish red. Fall foliage color is not the winterhazel's strong suit. Surely we can forgive them that weakness. Their leaves turn an unremarkable yellow or brown before dropping. Complement the winterhazels with evergreens to help show off that early bloom when other bushes are bare. Rhododendrons, with their broad evergreen leaves and similar site preferences, would make obvious, and excellent, companions to any winterhazel.
Bryant, Geoff and Tony Rodd. Trees and Shrubs: a gardener's encyclopedia. Buffalo, Firefly Books, 2011: ISBN 978-1-55407-836-3
Dirr, Michael A. Dirr's Encyclopedia of Trees and Shrubs. Portland, Timber Press, 201: ISBN 9780881929010
Fisher, Kathleen. Shrubs (Taylor's Guides. Boston, Houghton Mifflin, 2000: ISBN O-618-00437-8
Images courtesy of PlantFiles