Spring is finally arriving and the hazels and filberts (genus Corylus) are putting on a great show at the Arnold. Standing under a fabulous multi-stemmed European hazel (Corylus avellana, accession 98-2012*A) by Faxon pond, and looking up, it seems as if it is raining catkins filled with minute pollen bearing flowers (upper left image). And if looking at the male catkins of an American hazel (Corylus americana, 1229*A, received as a seed from Virginia in 1873, the second year of the Arboretum’s existence!) just yards away makes you think of birches in the spring, you are on the right track—for for indeed, hazels and filberts are members of the birch family (Betulaceae).
Like birches, individual Corylus plants create separate male (pollen bearing) flowers and female flowers (that will produce seeds in fruits). As with birches, it is easy to find the male catkins, but not so easy to find the female inflorescences. However, this pursuit is worth the hunt and once you find the female flowers, you will be richly rewarded.
Female flowers in compact inflorescences can be found inside small buds at various junctures along young woody stems. Since hazels and filberts are wind-pollinated, there is no need for showy flowers. Rather, what is called for is tons of pollen, and stigmas (the part of the female flower that receives pollen) with lots of surface area to intercept random pollen grains floating by in the breeze. In Corylus, the female flowers don’t even bother to emerge from the overwintering resting bud, except for a tuft of bright red stigmas. Bottom row: beaked filbert (Corylus cornuta—from woods at home), the Szechuan filbert (Corylus heterophylla var. sutchuenensis, 1094-89*A, collected as a seed in Zhejiang Province in 1989), and the Chinese filbert (Corylus chinensis, 493-37*B).
If you crave more Arnold Arboretum plant images, follow me on Instagram @nedfriedman.