Mike Heim's Tertiary Rewilding in Northern Wisconsin
Pt. 1: Torreya Taxifolia and Taxus Floridana

Hayward, Wisconsin

   Mike Heim in March 2017. He's a University of Minnesota horticulture grad and teaches science at a local tribal college.

Torreya taxifolia, along with Florida Yew, are two of the species he surmises lived in Wisconsin prior to the climatic cooling at the onset of the Pliocene (about 5 million years ago), which was then followed by the glaciation of the Pleistocene.

"My students and I are working on a long-term project in conjunction with the National Arboretum. It involves the naturalization of box huckleberry, a rare plant at present which likely thrived on the sandstone of northern Wisconsin during the Tertiary. (See my article "Return of the Ericads: Students Dig and Reestablish a Prehistoric Species".)"

• This webpage is Part 1 in his series, and it reports on his work with just the focal species of Torreya Guardians (and its rare cousin, Florida yew, which is also limited to the Apalachicola region of n. Florida).

• Mike's ongoing photos and reports of other Tertiary-age genera that were either extirpated from Wisconsin or fully extirpated in North America (surviving thru the cold times only in Asia) is accessible here as Part 2.

• The main planting location is within a mixed forest of acidic sandy-loam soil.


As of 2019, this is the map of all the NORTHERN-MOST successful plantings of Florida Torreya made and/or monitored by Torreya Guardians during the past 15 years.

Mike Heim's site is marked by the orange conifer symbol.


• JULY 2019 - A Florida torreya seedling after 3 winters in northern Wisconsin.


Mike Heim writes, "This was its third winter here and I don't give it any protection from the cold besides what Mother Nature provides. This past winter the temperature dropped to -36F with only 5 or 6 inches of snowcover. This last surviving GA torreya seedling was protected by snow, but not much — maybe an inch. This was our coldest winter since the 1990s.... This Torreya is the only survivor of two originals pictured in the March 2017 report below. (This is the seedling pictured in the left photo of 2017.)"

HOWEVER, "the June 2017 photos (below) were of a different, larger seedling. It died for no apparent reason. I wish I would have checked for rodent damage at the time, but only much later read about this problem." Deer herbivory is ruled out because an exclosure surrounds the plantings of Florida Torreya and Florida Yew.

• APRIL 2019 - Mike Heim sent an email report to Connie Barlow on 2 April 2019:

"I'm waiting for the snow to finally melt off of the T. taxifolia seedling and cuttings. The Taxus floridana all are in perfect condition after a -36F winter with not a whole lot of snow covering them."

• JUNE 2017 - The biggest of the two Torreya taxifolia seedlings (photo below), as of mid-June 2017:


• MARCH 2017 - It has been an extraordinary winter here. On December 18th the temperature dropped to -25F with only several inches of snowcover.  Heavy rainfalls resulted in the unprecedented disappearance of the snowpack in February.  Since then the bare ground and uncovered plants have had to endure temperature extremes seesawing back and forth between -5F to almost 60F and back again.  The sustained strong damaging winds are also unusual.

      PHOTO LEFT: Two of three potted seedlings of Torreya taxifolia, survived their first winter.

After having his rooted cuttings of Torreya taxifolia die during their first Wisconsin winter in 2010, Mike decided to plant specimens that had germinated from seeds (and therefore would have better root systems).

Summer of 2016, Mike obtained 3 potted seedlings, donated by Dawes Arboretum (Ohio) from seeds sourced by Torreya Guardians (Georgia provenance). One died in the spring (something about the microsite perhaps) and as you can see, the other two are thriving.

      • MARCH 2017 (continued)

LEFT AND BELOW: The Florida yew rooted cuttings (Taxus floridana) pictured in the 2010 photos below are still alive and growing.

Because they were rooted cuttings (not grown from seed) they will retain the horizontal growth form of the lateral branch cut from their mother tree.

A ground-hugging growth habit may be very advantageous in the north woods of Wisconsin — and for two reasons. First, snow cover will likely bury and thus protect it from extreme episodes of cold. Second, the snow will hide it from the winter-starved deer.


All of the Torreya taxifolia ended up dying as spring proceeded.

Photo left is one example of a dead or dying Torreya.

• APRIL 2010 (cont.)

LEFT: In contrast to the fate of Florida Torreya (dead at bottom of photo), the Asian species, Torreya nucifera, is thriving (green at photo top).

COMMENTARY - Funny it took until now (April 26, 2010) for the dying to become apparent.

Anyway, it was a good learning experience and shows that these highly endemic species became that way for a reason during the Pleistocene or perhaps even before.

On the other hand, maybe their northern populations were eliminated by environmental change and only the less hardy southernmost ones survived. Guess we might never know.

The good news is that several Torreya nucifera (Asian species) came through in perfect shape! The box huckleberries also came through this winter splendidly. My biology students collected baseline data on them last week and I'm thinking they'll put on lots of new growth and runners this summer — if the drought doesn't stay too severe.

• APRIL 2010 (cont.)

The Japanese species of genus Torreya, Torreya nucifera radicans, seems to thrive on the property.

• APRIL 2010 (cont.)

Taxus floridana post-winter.

Right-most shows more damage from exposure.

ABOVE (2 PHOTOS): Florida Yew rooted cutting after its first winter. This species is much more site-tolerant than Torreya and was exposed to minus 12F without injury.

• MARCH 2010

Torreya taxifolia rooted cutting after its first winter. It was covered by snow for 3.5 months.

The plants only survived the winter on steep slopes.

WWW www.TorreyaGuardians.org

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