Celtis is a genus of about 60-70 species of deciduoustrees, commonly known as hackberries or nettle trees, widespread in warm temperate regions of the Northern Hemisphere, in southern Europe, southern and eastern Asia, and southern and central North America, south to central Africa, and northern and central South America. The genus is present in the fossil record at least since the Miocene of Europe, and Paleocene of North America and eastern Asia.
Celtis species are generally medium-sized trees, reaching 10-25 m (35-80 ft) tall, rarely up to 40 m (130 ft) tall. The leaves are alternate, simple, 3-15 cm (-6 in) long, ovate-acuminate, and evenly serrated margins. Diagnostically, Celtis can be very similar to trees in the Rosaceae and other rose motif families.
Small flowers of this monoecious plant appear in early spring while the leaves are still developing. Male flowers are longer and fuzzy. Female flowers are greenish and more rounded.
The fruit is a small drupe 6-10 mm (- in) in diameter, edible in many species, with a dryish but sweet, sugary consistency, reminiscent of a date.
Caucasian hackberry (C. caucasica) with immature fruit
African hackberry (C. integrifolia)
Chinese hackberry (C. sinensis)
C. australis autumn leaves
^Keeler, Harriet L. (1900). Our Native Trees and How to Identify Them. Originally published by Charles Scribner's Sons, New York. Facsimile edition from a scan of the first edition published 2005 by the Kent State University Press, Ohio. ISBN0873388380. Available online through Google Books.
^MacPhail, M. K., N. F. Alley, E. M. Truswell and I. R. K. Sluiter (1994). "Early Tertiary vegetation: evidence from spores and pollen." History of the Australian Vegetation: Cretaceous to Recent. Ed. Robert S. Hill. Cambridge University Press. pp. 189-261. ISBN0521401976. Partially available on Google Books.
^Manchester, S. R., Akhmetiev, M. A., & Kodrul, T. M. (2002). Leaves and fruits of Celtis aspera (Newberry) comb. nov. (Celtidaceae) from the Paleocene of North America and eastern Asia. International Journal of Plant Sciences, 163(5), 725-736.
^Brower, Andrew V.Z. (2006). Problems with DNA barcodes for species delimitation: 'ten species' of Astraptes fulgerator reassessed (Lepidoptera: Hesperiidae). Systematics and Biodiversity4(2): 127-132. doi:10.1017/S147720000500191XPDF fulltext