Botanical Harvest: Cottonwood (Populus spp.)

 Cottonwood bud with resin in late winter

Cottonwood bud with resin in late winter

In the cold of winter, the cottonwoods keep spring wrapped up tight -- little buds waiting for just the right warmth to unfurl tiny perfect leaves.  You can smell their opening before you see it.  A dripping resinous, lush and honeyed smell like sun-warmed earth and new green things.  You might be tempted to call it the smell of spring itself.
 
This lovely sticky resin makes the base of an ancient salve.  Or at least the North American version of it.  There is some confusion around the famous biblical Balm of Gilead.  Botanical scholars believe the original Balm of Gilead to have been made using resin either from the Arabian Balsam (Commiphora gileadensis) or Turpentine (Pistacia terebinthus) tree, Mediterranean trees respectively from the Frankincense and Cashew families.  Modern references to Balm of Gilead usually refer to salves made from the resin of various cottonwood trees, the most fragrant being the Balsam poplar (Populus balsamifera) and Black cottonwood (Populus trichocarpa).  

 Cottonwood bud harvest for use in our Hand and Lip Balms

Cottonwood bud harvest for use in our Hand and Lip Balms

New Mexico has its own Balm of Gilead.  Our native Rio Grande (Populus deltoides ssp. wislizeni) and Plains (Populus deltoides ssp. monilifera) cottonwoods produce a beautiful waxier resin with all the same properties as their cousins and a unique New Mexico bosque fragrance.  In addition to this awesome perfume, cottonwood bud salve is also a wonderful balm to dry, cracked skin, being known for its antimicrobial, anti-inflammatory and analgesic properties. 

If you want to harvest your own resin, wait until winter is almost over and the buds are beaded with resin.  Search for wind fall branches or prune off just a few buds per branch, taking care to harvest lightly.  Fill your jar with resiny buds, pour in organic jojoba or fractionated coconut oil to cover and water bath the sealed jar on low heat for 8-36 hours.  Strain (and repeat with new buds if stronger fragrance is desired) and store in a cool, dark place.  This gently scented oil is a great moisturizer for face, body and hair.  At Dryland Wilds, we make both Cottonwood Bud lip balm and hand balm – a soothing spring perfume for dry winter lips and hands.  (Note: Those with aspirin sensitivities are advised to stay away from products made using this family, due to their salicylic acid content.)

 Cottonwood bud maceration in fractionated coconut oil

Cottonwood bud maceration in fractionated coconut oil

These desert river giants offer so much.  In addition to their perfumed resin, they also have super nutritious leaves, tasty catkins, famine-worthy inner bark and quite a bit of fluffy fiber that can, with patience be spun like cotton. Cottonwood leaves are reputed to be higher in protein than rice, corn, wheat, and barley – an interesting thought as we move towards eating more perennials.  Unless you are a beaver, these leaves are unpleasantly bitter eaten straight off the tree.  To make them both nutritious and delicious, boil leaves in a change of water before sauteing with other greens, using in a wilted salad or throwing in a smoothie.   If you are looking for a quick trail snack, go for the sweet, nutty catkins - those long, dangling, deep red flowers that come out a little later in the spring.  Taste from several trees to find the best.  Catkins are delicious raw, steamed, sautéed, baked, candied and batter-fried.   To harvest, clip them from hanging branches, shake off any resident bugs and sticky bud casings and prepare.  
 
New Mexico’s cottonwoods are undeniably cool.  In folklore they are associated with love and thought to draws lovers together.  (Take your sweetie or yourself on a Valentine’s Day picnic under the cottonwoods.  Smear your lips with our Cottonwood Bud Lip Balm and wait.  Let us know how it goes.)  In the bosque, these trees have the important job of shading the water and soil and sheltering and feeding a multitude of animals and plants that couldn’t survive without them.  The cottonwood is also classed as a “phyreatophyte” – simply meaning a plant that happily lives with its tap root in the water table.  Select phreatophytes have the ability to pump ground water up and release it in the higher, drier soil layers above - helping to keep the soil community around itself watered, even when there is no rain or snow.  Recent research is showing that certain species of cottonwoods fix nitrogen into the soil, similar to plants in the bean family.  Some cottonwoods can even fix nitrogen directly on their leaves.  So cottonwood - so cool.

 The fall colors of the New Mexican bosque. 

The fall colors of the New Mexican bosque. 

You can tell the health of a bosque by looking at the cottonwoods.  A balanced system should have cottonwoods at all stages of life, newly germinated babies as well as towering elders.  Unfortunately, that’s a rare sight these days.  In many riparian areas, only the beautiful old trees remain, holding down the fort next to downcut rivers and thick, non-native, opportunistic understories.  There is widespread concern about the possibility of invasive tamarisks drinking up the rivers, salting the soil and choking out the native cottonwoods.  This issue is way more complicated than it looks at first glance (stay tuned for the whole question-worthy and sordid history in a future Howl).  What's helpful to know here is that new research shows that the cottonwood can successfully out-compete even newcomers - even the terrifying tamarisk.  But only given that the floodplain is allowed to flood, something that the last century has designed against.

 Cottonwood, tamarisk, russian olive and willow growing alongside the Rio Ojo Caliente

Cottonwood, tamarisk, russian olive and willow growing alongside the Rio Ojo Caliente

Cottonwoods need the river’s flood cycle to reseed and grow new cottonwoods.  In the springtime, their fluffy airborne seeds are designed to germinate in spring flood-soaked soil.  Their tiny roots take this rare wet-warm-soil time to shoot downwards at incredible speeds, attempting to reach the water table and stabilize before the upper soil dries up.  Without the floodplain flooding, this Superwoman seed germination doesn't happen. 

Long story short - merely removing the hated tamarisk and russian olives (post-apocalyptic trees that can cope with our damaged, downcut watersheds) won’t bring back New Mexico’s beautiful giants. If we want a future with cottonwoods, we must allow our artificially straightened rivers to be their own true winding, flooding and beaver-filled selves. 


References (read more about the stuff mentioned above...)

Bhattacharjee, J., Taylor, J.P., Smith, L.M. et al. Biol Invasions (2009) 11: 1777. https://doi.org/10.1007/s10530-008-9357-4

Chew, M.K. J Hist Biol (2009) 42: 231. https://doi.org/10.1007/s10739-009-9181-4

Groom, N. (1981). Frankincense and Myrrh: A Study of the Arabian Incense Trade. London and New York: Longman, Librairie de Liban. ISBN 0-582-76476-9.

Doty, S., Sher, A., Fleck, N., Khorasani, M., Bumgarner, R., Khan, Z., Ko, A., Kim, S. and DeLuca T. (2018).Variable Nitrogen Fixation in Wild Populus. [online] Available at: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0155979 [Accessed 8 Jan. 2018]

Yu, T., Feng, Q., Si, J. et al. Plant Soil (2013) 372: 297. https://doi.org/10.1007/s11104-013-1727-8

Pfaf.org. (2018). Populus deltoides Eastern Cottonwood, Plains cottonwood, Rio Grande cottonwood, Necklace Poplar PFAF Plant Database. [online] Available at: https://www.pfaf.org/user/Plant.aspx?LatinName=Populus+deltoides [Accessed 1 Feb. 2018].

Wuehlisch, G. Von. (2018). Evidence for Nitrogen Fixation in the Salicaceae Family.  Indian Journal of Ecology, Vol.38(No.Special Issue), pp.pp.80-83.