Description: This is a small tree or woody shrub about 3-10' tall (rarely up to 20'). It has an erect and slender central stem with occasional ascending branches dividing into twigs and young leafy shoots. The branch bark is light gray to gray with whitened blotches. The twigs are light brownish gray to medium brownish gray with scattered small lenticels (air pores). Young shoots are light green to light reddish green and either glabrous (var. glabrata) or finely short-pubescent (var. lanceolata). Along the twigs and shoots are mostly alternate leaves (less often nearly opposite). These leaves vary in size from 1-3" and 0.33-1.0" across; they are typically 2-4 times as long as they are across. The leaf shape is lanceolate-elliptic to ovate-elliptic, and the leaf margins are finely serrate-crenate. Their upper surfaces are green to dark green and glabrous (hairless), while their lower surfaces are light green and either glabrous (var. glabrata) or minutely pubescent, especially along the veins (var. lanceolata). There are 4-7 pairs of veins along each leaf that arch toward its tip. The slender petioles are 3-9 mm. (0.12-0.36") in length; they are light green to light reddish green and grooved along their upper surfaces.
Lance-leaved Buckthorn is dioecious with male and female flowers on the same small tree or shrub; they occur in small clusters of 2-4 flowers or sometimes solitary. There are no peduncles, only pedicels that are quite short (2-3 mm. or 0.08-0.12" in length). The male flowers are about 3-3.5 mm. across, consisting of 4 yellowish green petals, 4 yellowish green sepals, and 4 stamens. The petals are ovate to triangular in shape. The female flowers are a little smaller in size (2.5-3.0 mm. across), consisting of 4 green to yellowish green petals, 4 green to yellowish green sepals, and a single style with a divided stigma. The base of each flower (hypanthium) is short-cylindrical to ovoid in shape. The flowers typically bloom in mid- to late spring for about 2-3 weeks. There is no noticeable scent. Afterwards, fertile female flowers are replaced by small spheroid drupes about about 4-6 mm. (0.16-0.24") across. Each drupe contains a single stone that is grooved on one side. The drupes become black at maturity. The root system is woody and branching; it doesn't form clonal offsets from underground runners.
Cultivation: The preference is full sun to light or partial shade and moist to somewhat dry conditions. The soil can consist of clay-loam to rocky material containing limestone or dolomite; soil that is calcareous and slightly alkaline is preferred. This small tree or shrub is easy to cultivate from small nursery plants; it is not an aggressive spreader.
Range & Habitat: The native Lance-leaved Buckthorn is uncommon in many areas of central and northern Illinois; otherwise it is largely absent It used to be more common in the past (see Distribution Map. Habitats include limestone glades, rocky ledges, thinly wooded bluffs, loess hill prairies along major rivers, gravel prairies, wooded ravines, bases of wooded cliffs, creek banks in woodlands, open seeps in upland woodlands, drier areas of fens, thickets, and woodland edges along roadsides. Higher quality habitats are preferred.
Faunal Associations: The flowers are cross-pollinated primarily by small bees and flies; both nectar and pollen are available as rewards to such floral visitors. These floral visitors include Halictid bees (including green metallic bees), Andrenid bees (Andrena spp.), flower flies (Syrphidae), flesh flies (Sarcophagidae), blow flies (Calliphoridae), and other flies. Long-tongued bees are uncommon visitors (Robertson, 1929; Krombein et al., 1979). Some insects feed destructively on Lance-leaved Buckthorn, but such records are sparse. The moth larvae of Apophthisis pullata and Nepticula rhamnicola mine the leaves of this woody plant, while an aphid, Macchiatiella rhamni, sucks on its plant juices (Needham et al., 1928; Hottes & Frison, 1931). Other insects that feed on buckthorns (Rhamnus spp.) include Aphis nasturtii (Buckthorn Aphid), larvae of Triphosa haesitata (Tissue Moth), and armored scale insects (Cranshaw, 2004; Pepper, 1965; ScaleNet, accessed 2014; Covell, 1984/2005; Wagner, 2005). Among vertebrate animals, the fruits of Lance-leaved Buckthorn are undoubtedly dispersed by several species of birds; one of them is the Brown Thrasher (Martin et al., 1951/1961). DeGraaf (2002) lists several birds that eat the fruits of buckthorns (Rhamnus spp.): They include the Cedar Waxwing, Baltimore Oriole, Gray Catbird, Northern Mockingbird, Brown Thrasher, Ring-necked Pheasant, Pileated Woodpecker, Downy Woodpecker, Hairy Woodpecker, Hermit Thrush, Wood Thrush, American Robin, Great Crested Flycatcher, and Eastern Kingbird. Because the foliage and bark of buckthorns are toxic, mammals tend to avoid them. However, the White-tailed Deer browses on the twigs and the Cottontail Rabbit gnaws on the bark during winter as a source of emergency food.
Photographic Location: The wildflower garden of the webmaster in Urbana, Illinois.
Comments: Lance-leaved Buckthorn is an inconspicuous small tree or shrub that is easily overlooked, except when it is in flower. It is also rather easy to confuse this uncommon native woody plant with the invasive buckthorn species (Rhamnus spp.) that have been introduced from abroad, such as Rhamnus cathartica (Common Buckthorn), Rhamnus japonica (Japanese Buckthorn), Rhamnus davurica (Davurica Buckthorn), and Frangula alnus (Glossy Buckthorn). Lance-leaved Buckthorn can be distinguished from the non-native Rhamnus spp. by its alternate leaves, whereas the latter have opposite leaves. The remaining introduced species, Glossy Buckthorn, differs from Lance-leaved Buckthorn by its 5-lobed flowers, smooth leaf margins, and stones that lack grooves.