Guide

Look closerPlants

Winter catkins on hazel, alder, birch, and hophornbeam

December to March

Hazelnuts, alders, birches, and hophornbeam make their male catkins the summer before they flower and leave them hanging, closed and firm, on the twigs all winter. In spring the same catkins lengthen, loosen, and shed pollen, with hazels and alders going first, before their leaves.

Why this time of year

Once the leaves are down, these catkins are easy to see at the tips and sides of bare twigs. They were formed during the last growing season and will stay closed until spring warms them.

How to notice it

  1. Along a woodland edge, a wet thicket, or a row of birches, look at the twig tips for small, stiff, sausage-shaped catkins, alone or in small clusters.
  2. Try to sort them by plant: hazels carry theirs along the sides of the twig, birches and hophornbeam carry theirs at the tip, and alders hang them in clusters next to small, dark, woody cones.
  3. Pick one twig you can reach and check it every couple of weeks through the winter. The catkins should look the same until spring.
  4. In early spring, watch for that same catkin to grow longer, turn floppy and yellowish, and puff pollen when you tap the twig. On hazels, look closely for tiny red threads nearby, which are the female flowers.

Try this with kids: Find a twig with catkins and count how many hang together. Hophornbeam often has three, like a little bird's foot.

Word to know: A “catkin” is a slender, hanging spike packed with tiny flowers.

Sources

  • efloras.orgFlora of North America, Betula: male catkins 'formed previous growing season and often exposed during winter, expanding with leaves'.
  • efloras.orgFNA, Alnus: for the group incl. A. incana and A. serrulata, catkins develop 'during the growing season prior to anthesis, with these fully exposed during winter'; male catkins expand 'before or with leaves'.
  • efloras.orgFNA, Corylus: male catkins 'formed previous growing season and exposed during winter, expanding well before leaves'; 'the staminate catkins are formed during the summer and are exposed through the winter prior to anthesis'.
  • efloras.orgFNA, Ostrya: male catkins 'formed previous growing season and exposed during winter, expanding with leaves'; 'unlike Carpinus'.
  • efloras.orgFNA, Carpinus (contrast): male catkins 'enclosed within buds throughout the winter prior to anthesis (in Ostrya, these are exposed during the winter)'.
  • efloras.orgFNA, Corylus americana: 'Flowering very early spring.' Range includes 'Mass.'
  • efloras.orgFNA, Alnus incana: male catkins 'formed season before flowering and exposed during winter. Flowering before new growth in spring.'
  • dendro.cnre.vt.eduVirginia Tech Dendrology, hophornbeam: 'males are preformed catkins, 1/2 to 1 inches long, in clusters of 3's (resemble birds toes), present throughout the winter'.
  • dendro.cnre.vt.eduVT Dendrology, beaked hazel: 'males are preformed, light brown-gray catkins ... in clusters of two or three near branch tips'; females 'bright red stigma'; males elongate 'in early spring before the leaves'.
  • dendro.cnre.vt.eduVT Dendrology, gray birch: 'preformed male catkins near the end of the twig, 3/4 inch long, usually single'; 'elongate (males) in early spring'.
  • dendro.cnre.vt.eduVT Dendrology, speckled alder: 'preformed male catkins are 1/2 to 1 inch long, slender and green'; cone-like fruit 'persistent'.
  • umass.eduUMass Extension Landscape Message, April 10, 2026, East (Boston) report: American hazelnut among 'Early trees and shrubs beginning to bloom' (late March to first week of April).
  • umass.eduUMass Extension Landscape Message, April 21, 2023, Long Hill (eastern MA): 'American filbert ( Corylus americana )' in bloom.
  • gobotany.nativeplanttrust.orgGo Botany: American hazelnut 'widespread (S-rank: S5)' in Massachusetts; forest borders, thickets, fields, hedgerows, roadsides.
  • gobotany.nativeplanttrust.orgGo Botany: speckled alder habitats 'shores of rivers or lakes, swamps, wetland margins'.

Checked against these sources on October 23, 2026.

In the guide for December, January, February, March

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