Telling Black Walnut and Butternut Apart by Their Leaflets

Walk through the towering eucalypts of the Dandenong Ranges or the remnant bushland hugging Sydney Harbour, and the canopy overhead feels unmistakably Australian. Yet tucked inside some of our heritage orchards, university arboreta, and well-tended suburban blocks are two deciduous giants with a North American accent: black walnut and butternut. Both belong to the genus Juglans, both drop heavy nuts in autumn, and both carry long pinnately compound leaves that have tripped up countless bushwalkers, Landcare volunteers, and curious gardeners trying to name what is shading their chook run.

Because the bark, twigs, and fruit of mature trees share so many overlapping features, the most reliable way to tell these relatives apart without climbing the canopy is to look closely at the leaves, and more specifically at the shape and arrangement of the leaflets along the central stalk. A little practice in reading leaf architecture makes it possible to sort them out with confidence, even before the first nuts fall. This guide walks through the field marks that matter, with a focus on leaflet shape that an observer in southern Australia can practise on a single quiet afternoon.

The shared architecture of Juglans leaves

Both black walnut (Juglans nigra) and butternut (Juglans cinerea) produce pinnately compound leaves arranged in an odd-pinnate pattern, meaning leaflets are paired along a central rachis with a single leaflet capping the tip. Mature leaves typically carry somewhere between 11 and 23 leaflets, and each leaflet is attached by a short stalklet to the main axis. The overall silhouette of a single leaf is long and feather-like, often reaching 30 to 60 centimetres in fully grown trees.

This shared blueprint is the reason casual observers confuse them. A leaf pulled from either tree feels similar in weight, casts a similar dappled shadow, and flutters with the same slightly oily gloss. Beyond the obvious, the way the leaflets attach, the proportions of width to length, and the way the leaf ends all carry diagnostic weight, and these features hold up across seasons because walnut foliage is deciduous and visible in Australian gardens from late spring through the first chills of May or June.

Counting leaflets and spotting the terminal one

The single most useful field mark for separating these two species is the presence or absence of a terminal leaflet, the small, distinct leaflet that sits at the very tip of the compound leaf where the rachis ends. In black walnut this terminal leaflet is almost always present, giving the leaf a tidy, finished look with an odd number of leaflets across the whole structure. Butternut leaves frequently lack this terminal leaflet, leaving the rachis to end abruptly in a small pair of side leaflets or a slightly stunted tip, which produces an even count along the stalk.

This single character, sometimes called the apex character, holds true across most of the range of both species and works even on saplings only a metre tall. For Australians trying their hand at identification, it is worth remembering that trees grown outside their native range, including specimens in the Royal Botanic Gardens Melbourne or in cool-climate collections around Hobart, tend to express these traits just as strongly as their North American cousins. Grab a leaf, lay it on a flat rock, and count from the base upward; the way the leaf ends usually settles the question within seconds.

Leaflet shape, margin and surface texture

Beyond the tip, leaflet shape itself provides strong supporting evidence. Black walnut leaflets are typically lanceolate to narrowly ovate, with the widest point usually below centre, tapering to a long drawn-out tip. The margins are finely and sharply serrate, almost like the teeth of a small saw, and the upper surface is mostly smooth and a deeper, slightly glossy green. Butternut leaflets, by contrast, tend to be broader, more oblong or elliptic, and the serrations along the edges are coarser and more irregular, with rounded teeth that look softer at a glance.

Texture is another helpful clue. Young butternut leaves and the expanding shoots around them often carry fine sticky hairs, giving the new growth a faintly tacky feel and a pale grey-green cast. Black walnut new growth is also downy, but the hairs are shorter, and the leaves mature to a smoother, darker finish. Press a leaflet between thumb and forefinger and crush it gently; the aromatic compounds differ slightly between the two, with butternut smelling a little sweeter and more resinous and black walnut carrying the sharper, more turpentine-like scent familiar from the timber trade.

Twig colour, pith and supporting clues

When leaflets alone leave room for doubt, twigs can firm up an identification. Black walnut twigs are sturdy, often a warm grey-brown to orange-brown, and the pith inside is a chambered, pale buff colour divided by thin woody plates, a feature many bushcarers remember once they have cut a few samples. Butternut twigs are similar in build but the pith is a dark chocolate brown, solid rather than chambered, and the outer bark on young growth often carries a slight pinkish or grey cast that distinguishes it from the ruddier tones of black walnut.

Other supporting characters include the nuts themselves, which drop well after leaf fall in Australian conditions. Black walnut husks are thick, rounded, and tough to crack, while butternut husks are elongated, sticky, and clingier to the shell. Fruit shape is not always available during a leaf-focused outing, but when present it complements the leaflet evidence nicely. A small hand lens can also help reveal the tiny hairs along the leaflet veins of butternut, which are often absent or sparse on black walnut, particularly as the season progresses into the cooler months.

Where these trees fit in Australian landscapes

Neither black walnut nor butternut is native to Australia, but both appear in the catalogue of trees that councils and community nurseries sometimes stock for particular purposes. Heritage orchards in the Adelaide Hills, the Central Tablelands of New South Wales, and parts of Gippsland occasionally grow black walnut for its prized timber, while butternut pops up in cool-climate collections and university trial plantings around Canberra and the southern highlands. Local Landcare networks and Bushcare groups, especially those working along creek restoration projects, generally focus on indigenous species, yet reading the broader walnut family sharpens identification skills that translate to local natives such as the Quandong or various native figs that share compound or lobed foliage.

For Australians interested in the wider picture of temperate deciduous forestry, watching how these introduced species behave in our climate offers a useful reference point. Black walnut struggles in the humid subtropics around Brisbane but thrives in the cooler Mediterranean-style climates of Perth and parts of southern Victoria, where winter chill suits its rhythm. Knowing where they grow well here also helps with biosecurity awareness under state-level frameworks like the NSW Biosecurity Act and similar legislation across other states, since tracking which non-native trees thrive locally is part of protecting remnant vegetation from potential pests and pathogens.

Practical leaflet habits for confident field identification

Take a small notebook and a hand lens on your next walk. Practising a few habits turns uncertain guessing into confident naming.

Always collect a whole compound leaf, not a single leaflet, so the terminal character can be checked.
Photograph the leaf flat against a ruler or a known object to record scale, useful when comparing with reference images later.
Note whether the leaflets are paired evenly along the rachis or whether some pairs are missing or staggered.
Crush one leaflet and smell it; the difference between the sharper black walnut scent and the softer butternut note is surprisingly consistent.
Check the underside for fine hairs, especially along the midrib and veins, which lean towards butternut when abundant.
Cross-reference with twig pith colour whenever a fallen twig lies nearby, since the chambered buff pith of black walnut is distinctive once seen.

Bringing these habits together on a quiet afternoon in a local park, a heritage garden, or a managed creekline will quickly sharpen the eye. Native hardwood identification skills like these feed directly into the kind of careful observation that volunteers bring to streamside planting days, where every seedling placed beside a creek helps stabilise banks, filter runoff, and rebuild habitat along waterways.

Put these observation skills to use for a living watershed today. Join a Growing Native seed collection day, family-friendly planting event, or workplace team outing by signing up through the volunteer register, and help restore forests and waterways across the Potomac watershed one native seedling at a time.