Many different species of shrubs have thorns or spines, some of which grow on their stems or branches and others that grow on their fruit husks. When you're attempting to identify a shrub with thorns, you cannot rely on the thorns alone to make an accurate identification. You'll need to study a variety of other characteristics to properly identify the shrub. The most popular shrubs with thorns that are found in the wild or in landscapes include shrubs like hawthorns, barberries, roses, wild plums, as well as raspberries and blackberries.
Identify shrubs with thorns by their size. For example, wild plum shrubs (Prunus americana) grow 15 to 25 feet tall with short trunks, while the buffaloberry shrub (Shepherdia argentea) grows to about 10 feet tall and 8 feet wide.
Notice where the thorny shrub is growing to identify it. For example, hawthorns (Crataegus sp.) can grow in a wide variety of soil types, but they're often found growing wild along roadsides and in rough pastures. Wild plums usually grow in moist, rich soils along stream banks or in thickets.
Study the leaves to make an identification. Hawthorns have leaves with notched edges that grow in an alternate fashion along the stems, while wild plums have 2- to 5-inch-long and 2-inch-wide, oval, narrow-pointed leaves with double-toothed edges. Buffaloberry shrubs have silver leaves that are arranged opposite each other in pairs along the stems. European barberries (Berberis vulgaris) have leaves edged in prominent, spiny teeth, while the Japanese barberry (B. thunbergii) has smooth-edged leaves.
Identify the shrub with thorns by looking at its fruits. Hawthorn shrubs bear 1/4- to 3/4-inch-diameter fruits that are globe-shaped or oblong, while wild plums produce 3/4-inch-wide, orange-red drupes that ripen in late summer. Buffaloberry shrubs bear fleshy, yellowish-red fruits with an inner pit.
Study the thorns to identify the shrub. Wild plum shrubs have thorns on their trunks, while buffaloberry shrubs have thorny projections on their branches. Raspberry and blackberry shrubs (Rubus spp.) have spines that separate easily from their stems.