The Craigia Page

Introduction

Craigia W.W. Smith & W.E. Evans is one of the 3 living genera of trees which comprise subfamily Tilioideae of the angiosperm family Malvaceae. It is more closely related to Tilia (limes), than to the 3rd genus (Mortoniodendron).

As a living genus it is confined to southern China and adjacent northern Vietnam. where there are 1 or 2 living species (one species has not been seen since discovery and may be extinct. Descriptions of both species, Craigia yunnanensis W.W. Smith & W.E. Evans and Craigia kwangsiensis Hsue can be found in the recent Flora of China [1].

In earlier periods the genus had a much wider range. It was common in the Tertiary of western North America, Europe and Asia. Extinction in Europe may be part of the widespread depauperisation of the European flora as a result of the Pleistocene glaciations; extinction in North America appears to be have earlier. The sister group, Tilia, is still present in Europe (and Eastern North America) but shows its greatest diversity in temperate East Asia.

Craigia is also a genus of amoebas.

Description

Craigia are deciduous trees. The living species have long petiolate leaves with elliptic or oblong blades and denticulate margins.

Living Species

Craigia yunnanensis W.W. Smith & W.E. Evans
dian tong

Craigia kwangiensis Hsue
gui dian tong

Fossil Species

A 2005 review [2] conservatively ascribed fossils of Craigia to two species - Craigia bronnii of western Eurasia, and Craigia oregonensis of east Asia and North America. Subsequently fossils of Craigia were also discovered on Hainan, and described as Craigia hainanensis [a].

Craigia bronnii Kvaček, Bužek & Manchester

The European Craigia bronnii is known from flowers, fruits and pollen. The fruits were previously known as Pteleaecarpum bronnii, Pteleaecarpum europaeum or Ulmus bronnii, and the flowers as Tilia gieskei. Leaves referred to Dombeyopsis lobata Unger may also belong to this species. Leaves assignable to Dombeyopsis lobata have also been placed in Dombeyopsis grandifolia Unger, Dombeyopsis sidaefolia Unger, Dombeyopsis tiliaefolia (A. Braun) Unger, Ficus dombeyopsis Unger, Ficus tiliaefolia (A. Braun) Heer, Cecropia europaea Ettingshausen, Cecropia heerii Ettingshausen and Sterculia dombeyopsis (Unger) Schimper [3].

Craigia bronnii is recorded from late Eocene and Early Oligocene of Spitsbergen, and from around 60 Oligocene to Pliocene localities in France, Italy, Germany, the Czech Republic, Poland, Slovakia, Austria, Slovenia, Hungary, Bosnia, Serbia, Romania, Moldavia, Bulgaria and Greece, and from a single Miocene site in Georgia [2].

Craigia oregonensis (Arnold) Kvaček, Bužek & Manchester

Craigia oregonensis was previously known as Pteleaecarpum oregonensis Arnold.

Craigia oregonensis is recorded from Palaeocene to Miocene sites in Kazakhstan, Manchuria, North Korea, Hokkaido, Sakhalin, Primorye, Kamchatka and arctic Siberia, and from Eocene and Oligocene sites in British Columbia, Oregon, Washington, Idaho, Montana and Utah [2].

Craigia hainanensis Jianhua Jin, T.M. Kodrul, Wenbo Liao & Xin Wang

Craigia hainanensis is found in the Eocene (Changchang Formation) of Hainan [a].

References

Song Zhi-chen, Wang Wei-ming and Huang Fei, Fossil Pollen Records of Extant Angiosperms in China, Bot. Rev. 12: 248-249 (2004)
Kvaček, Z., S.R. Manchester, and M.A. Akhmetiev, Review of the fossil history of Craigia (Malvaceae s.l.) in the northern hemisphere based on fruits and co-occurring foliage, Modern problems of Palaeofloristics, Palaeophytogeography, and Phytostratigraphy 114-140 (2005)

Bibliography

Jianhua Jina, T.M. Kodrul, Wenbo Liao & Xin Wang, A new species of Craigia from the Eocene Changchang Formation of Hainan Island, China, Rev. Palaeo. Palyno. 155(1-2): 80-82 (2009)
Call, Victor B. & Dilcher, David L., Fossil Ptelea Samaras (Rutaceae) in North America, Am. J. Bot. 82(8): 1069-1073 (1995)
Buzek, Cestmir, Kvaček, Zlatko & Manchester, Steven R., Sapindaceous Affinities of the Pteleaecarpum Fruits from the Tertiary of Eurasia and North America, Bot. Gaz. 150(4): 477-489 (1989)