Can bald cypress cross with China fir? The answer is I doubt it. An interesting intergeneric hybrid, X Taxodiomeria peizhongii Z.J.Ye, J.J.Zhang et S.H. Pan was touted to have been created in Nanjing, China in 1963. It was reported as a cross between Taxodium distichum var. mexicanum (Carriere Gordon) and Cryptomeria fortunei Hooibrenk ex Otto et Dietr. I first looked at the tree up close over a decade ago in Nanjing, China. I secured the plant for the SFA Gardens in 2012 as graft wood from Yongfeng Nursery, Ninghai, China. I took images of a number of the larger grafted trees and found the tree to certainly be different in appearance than most Taxodiums, more pond cypress like and certainly devoid of what I thought was any Cryptomeria genetics. Back at SFA Gardens, the grafts stuck and nine plants have found a home here in the Pineywoods. They are prospering in several locations and growing well. I have been unable to root them.
I learned that there were less than 50 viable seed after an extensive tree pollination and bagging protocol. From what I was told, the seedlings were grown and multiplied by cutting propagation to about 2000 total plants. Those were planted, observed, and somewhat forgotten, perhaps because they did not exhibit exactly what the Chinese foresters were seeking: a fast-growing deciduous conifer for roadside, canalside, streamside, and as a specimen tree or grove in public areas. A major reason that this particular tree may not have “taken hold” in the nursery industry in that region may be that there was already plenty of excitement with other deciduous conifers. After all, the Chinese had plenty of Taxodiums, straight Cryptomerias, Metasequoia, Glyptostrobus, Deodar cedar, and all of their own juniper world to work with. Another reason for interest in the hybrid, the central government’s effort to manage coastal wetlands as an agro-forestry-industrial resource included big funding of the coastal windbreak forest project. The project includes hurricane-proof, salt-proof buffers on the inland side of massive concrete dikes. Other genotypes showed more promise for that effort. Still, the tree was rediscovered in Shanghai and then promoted heavily as the lion-tiger of the big tree world. The introduction by botanists from the Shanghai Botanical Garden was received with much excitement in the conifer world and the tree was given high billing, bands and parades.
The purported hybrid of Taxodium and Cryptomeria was awarded a patent in 2007 in the USA as follows:
×Taxodiomeria peizhongii tree named ‘Dongfangshan’ US PP17767 P3
Abstract: ×Taxodiomeria peizhongii is a distinct and new above ground nontubular propagated cultivar comprising a tall semi-deciduous arbor tree providing a high view. ×Taxodiomeria peizhongii is well suited for afforestation in the city and has many good properties such as fast growth, wide adaptability and strong stress resistance. Its main characteristics include: (1) its base of stem is round and regular without buttress roots; (2) its bark cracks into flakes; (3) there are several main crotches five to eight meters above ground, and its canopy is nearly elliptic shape; (4) there are only male conglobate flower and no female conglobate fruit on the adult tree, and it cannot reproduce with sexual propagation manner. It possesses additional good properties including enhanced saline tolerance (salt content is below about 3.9%), alkali tolerance (7≦pH≦8.9), moisture resistance and good (pleasing visual) landscape effect.
As for the history of this Taxodium X Cryptomeria cross, I was told that “in a later inventory, only 800 of the “hybrids” were found to have made it into mature trees. Evidently, over the years there has been some debate on whether all were “true hybrids”, or perhaps some were “false hybrids.” I have seen the large ‘Dongfangshan’ tree at the Nanjing Botanical Garden and it appeared more MC-like than Cryptomeria-like, but the argument has been made in Chinese research there’s more contribution from the male parent to the tree and foliage form of the seedling. At any rate, the hybrids are semi-evergreen in Nanjing, Shanghai, and other locations in that region. The trees are reported to grow fairly fast, hold up to strong winds, and have no butswells and buttresses. The trunk is usually divided at a height of 5-8 m into two or more primary branches. They thrive in wetlands and saline sea-shores with a soil pH ranging from 6.5 to 8.6. The trees can grow in saline soil with 4 ppt (68 moles×m-3) salt. They are useful for landscape planting as well as for large-scale windbreaks in reverie and coastal regions (Zhang J et al. 2003).
After languishing for roughly two decades, the Chinese have taken a new look at the cross. In one sampling, Chen Y et al. (2002) conducted RAPD analyses on genetic polymorphisms of twelve of the genotypes to identify their relationships. These genotypes included eight suspected hybrid MC forest samples, the hybrid female parent—MC, and the same class of hybrid male parent—Cryptomeria fortunei Hooibrenk and sugi C. Japonica (L.f.) D.Don. The results revealed that “the genetic relationship of sample No.11 in three Cryptomeria genotypes is the closest to the original male-parent; samples No.1, 4 and 9 are most possibly the true hybrid MC populations; sample No.5 may be the false hybrid.”
However, the authenticity of this controversial intergeneric hybrid (X Taxodiomeria peizhongii Z. J. Ye, J. J. Zhang et S. H. Pan) has been questioned by Chinese scientists at the Nanjing Botanical Garden. To confirm the authenticity of the intergeneric hybrid, scientists there analyzed the rbcL gene and the internal transcribed spacer (ITS) of 26S–18S ribosomal RNA gene of the three species using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and arbitrarily primed PCR (AP-PCR), and obtained the following results: “(1) Taxodiomeria peizhongii had the same RFLP maps of the rbcL gene and the ITS as MC, but was different from C. fortunei; (2) a 311-bp PCR amplification product was obtained in C. fortunei by AP-PCR of ITS, but was not found in Taxodiomeria peizhongii. Their results have demonstrated that C. fortunei did not provide any genome for Taxodiomeria peizhongii, implying that T. peizhongii is not an intergeneric hybrid between the two species” (Ling Y et al. 2006).
In 2015, Yuhong Zheng, a visiting scientist from Nanjing studied 136 genotypes of Taxodium in a genetic analysis here at SFA Gardens. She concluded that ‘Dongfangshan’ did not have Cryptomeria genes to warrant its veracity as a hybrid. The mystery continues, but whatever the final verdict, the story proves that plants always have stories and this is just one of the more interesting mysteries, at least to the very few discriminating coniferphiles that find Taxodiums the holy grail of trees.
Ling, Y., W. Lu, F. Lu, Y. Wang, J. Chen, and W. Zhang. 2006. PCR-RFLP and AP-PCR of rbcL and ITS of rDNA show that ×Taxodiomeria peizhongii (Taxodium × Cryptomeria) is not an intergeneric hybrid. J Integrat Plant Biol 48(4), 468-472.
Yin, Y. 2005. Personal communication. Nanjing Botanical Garden, PO Box 1435, Nanjing, CN
Yuhong Zheng, Bea Clack, Yin Yunlong, David Creech. 2016. Genetic Diversity of a Range of Taxodium distichum Genotypes and Cultivars Based on ISSR Marker. Oral presentation at the annual conference of the American Society for Horticultural Science Southern Region. San Antonio, TX.
Zhang, J., S. Pan, W. Zhu, H. Niu, Z. Ye, J. Zhu, and P. Hu. 2003. Taxodiomeria (Taxodiaceae), an intergeneric hybrid between Taxodium and Cryptomeria from Shanghai