Palm Tree Identification and Pruning of Native and Naturalizable Palms

Summary: Co-authors A.D. Ali and Leonard Burkhart, Jr. of The Davey Institute discuss palm tree identification and pruning of native and naturalizable palms.

California fan palm (Washingtonia filifera) is the only palm native to the western U.S. and is prone to pink and bud rots; California fan palms in Palm Canyon, south of Palm Springs, Riverside County, southern California; March 2005: Stan Shebs, CC BY SA 3.0 Unported, via Wikimedia Commons

The Merriam-Webster Dictionary definition of trees as woody perennials whose single main stems assemble few or no lower branches assists palm tree identification, according to an article in Arborist News August 2017.

The 2,700-some species, unlike hardwoods and softwoods, bear conductive phloem and xylem tissue-filled vascular bundles, living outer pseudo-bark, no cambium or heartwood and one growing point. Crowns atop trunks rooted adventitiously cluster immature green, ripe black-brown, 0.5- to 1-inch (1.27- to 2.54-centimeter) fruits and small, stalked, white or yellow flowers. Compound leaves described as palmate (fan-like) or pinnate (feather-like) fronds display leaflets that defer to induplicate (v-shaped) or reduplicate (upside-down v-shaped) attachments from rachis (central ribs).

Frond shapes, leaflet attachments to smooth or spiny, trunk-attached petioles and trunk marks from circular- or diamond-shaped leaf scars emerge as aids in palm tree identification.

Proper pruning of dead or diseased foliage follows downward paths from above and outside trunk-encircling frond skirts and forms horizontal, 9:00 to 3:00 clock face-like attachments.

Pruning guards broken, freeze-, storm- or wind-damaged green compound leaves and even healthy fronds that generate no interference with or risk to people, structures and utilities. Pineapple pruning hones boots (persistent leaf bases) into bulbous shapes that harbor ivy, mushrooms, scorpions and snakes and that hydraulic pruners or pruning spades hack off. Proper treatment of heavy palm tree fruits involves applying the growth regulator ethephon to determinate blooming, regular flowering stalks and pruning indeterminate blooming, irregularly flowering stalks.

A.D. Ali and Leonard Burkhart, Jr. of The Davey Institute juggle 15 species in Palms: Woody Giants of the Monocots, Part I: Identification and Pruning.

Bismarck and king palms keep owners respectively stressed over pink rot, self-pruned foliage and spider mites and over 20-foot (6.096-meter) canopies too wide for small yards.

Cold and part-shade tolerances link blue hesper palms, with forked petiole thorns, and Chinese windmill palms, with brown fibers encircling slender trunks and graying with age. Fruits from Guadalupe palms, survivors of overgrazing by introduced goats on Mexico's namesake island, and from pindo palms make respectively date-like jams and pineapple-apricot-like jellies. Coconut oil, fruit husk fiber for manufacturing, edible fruit and sap boilable and fermentable into wine number among the respective coconut and Chilean wine palm products.

Proper palm tree identification operates against serious landscaping problems by optimizing accurate matches of correct palms in sustainable coastal outdoor and inland indoor North American environments.

Canary Island date palms prove particularly prone to lethal yellowing, palm leaf skeletonizer, palmetto weevil and, with Cuban royal palms, to basal stem and bud rots. Sabal palm buds (hearts) and true date palm fruits respectively qualify as consumable in salads and stews and as edible only from manually pollinated female trees. Older and younger fronds reveal frizzle-top symptoms in potassium-needy Cuban royal palms and, in alkaline soils, manganese-poor queen palms whose fruit litter rivals true date palms. California and spiny Mexican fan palms respectively suffer from pink and bud rots even though the former shows little of the latter's diamond scale fungus resistance.

Proper palm tree identification and maintenance treats California fan and Florida sabal palm trees as North American natives and the article's 13 other species as naturalizable.

North American native sabal palms (Sabal palmetto) may display bootjacks, a basketweave effect of persistent leaf bases (left), or smooth trunks after natural falloffs of leaf bases (right); sabal palms along Cruickshank Trail, Merritt Island National Wildlife Refuge, Titusville, Brevard County, central east Florida; Saturday, Oct. 1, 2016, 10:06:46: Katja Schulz (treegrow), CC BY 2.0 Generic, via Flickr

Acknowledgment

My special thanks to:
talented artists and photographers/concerned organizations who make their fine images available on the internet;
University of Illinois at Urbana-Champaign for superior on-campus and on-line resources.

Image credits:

California fan palms (Washingtonia filifera) in Palm Canyon, south of Palm Springs, Riverside County, southern California; March 13, 2005: Stan Shebs, CC BY SA 3.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Palm_Canyon_water_3.jpg

sabal palms along Cruickshank Trail, Merritt Island National Wildlife Refuge, Titusville, Brevard County, central east Florida; Saturday, Oct. 1, 2016, 10:06:46: Katja Schulz (treegrow), CC BY 2.0 Generic, via Flickr @ https://www.flickr.com/photos/treegrow/30169119246/

For further information:

Ali, A. D.; and Burkhart, Leonard Jr. August 2017. "Palms: Woody Giants of the Monocots, Part I: Identification and Pruning." Arborist News 26(4): 12-20.

Craft, Paul; Robert Lee Riffle; Scott Zona. 2003. The Encyclopedia of Cultivated Palms. Second edition. Portland OR: Timber Press.

Gilman, Ed. 2011. An Illustrated Guide to Pruning. Third Edition. Boston MA: Cengage.

Hayes, Ed. 2001. Evaluating Tree Defects. Revised, Special Edition. Rochester MN: Safe Trees.

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