Monday, January 18, 2010

The Avocado Family


A genus of nearly 200 species of evergreen trees native to tropical and warm temperate regions of North America, Asia and the Canary Islands.
They prefer a sunny site protected from excessive wind on a very well drained, fertile soil ( however some species are exceptions and grow in swamps ).
Propagation is from cutting or seed.
A new fungal disease has been accidently introduced to the southern U.S. and is threatening to wipe out native Persea, Umbellularia and even Sassafras in North America. Laurel Wilt fungus gets introduced into the tree from the non native Ambrosia Beetle which is a wood boring insect. The fungus is similar in effect to Dutch Elm Disease and the growth of the fungus cuts off the trees sap flow and kills the tree. There are continuing efforts to control this disease.

Persea americana ( Avocado )
Also called Alligator Pear. A fast growing, rounded, large evergreen tree native to the Caribbean and Central America. Some records include: fastest recorded growth rate - 4 feet; largest on record - 133 x 75 feet with a trunk diameter of 5 feet. Grafted trees generally are much smaller, often not even reaching 40 feet. Avocados can be grown indoors but generally lack vigor and fruit due to their need for direct sunlight. Avocado trees cast dense shade. Grafting is often done because seed grown trees take longer ( around 7 years ) to fruit.
The elliptical leaves are up to 18 x 5 inches in size though are usually much smaller. The leathery foliage is deep green above, blue-green beneath.
The yellowish green flowers are borne in panicles.
They are followed by large, pear shape or rounded deep green fruit up to 8 inches in length. The fruits are edible and very healthy. They are rich in Vitamin E, Vitamin E, Vitamin K, Potassium, Fiber and healthy fats.
Trees will produce individually however production is usually better with multiple trees to cross pollinate. Pick the fruit when mature and firm, the Avocado fruit continue to ripen off the tree. The average mature avocado tree produces up to 1200 avocados annually. Yields up to 220 pounds per tree are known.
Hardy zone 9 to 11 tolerating as low as 26 though a very few cultivars down to 18 F . Prefers soil PH 5 to 6.5 and hates heavy clay. Avocado tree needs well drained soil and dies where the water table is too high in the winter. They require about 1 inch of water per week, even when mature.

* photos of unknown internet source

* photos taken on Jan 3 2011 @ Deerfield Beach Arboretum, Florida

Scab resistant

Self pollinating. Tolerates as low as 18 F

Self pollinating. Tolerates as low as 18 F

Persea borbonea ( Red Bay )
A very dense, handsome, medium size, evergreen tree native to low sandy well drained forests of the southern U.S. from central Texas to North Carolina up to coast to Delaware, where it is rare and local throughout. It is also found in pine scrub and sand dune forests in the wild. Some records include: fastest recorded growth rate - 3 feet; largest on record - 100 x 70 feet with a trunk diameter of 4.4 feet. Red Bay makes an excellent ornamental shade tree.
The thick leathery elliptical leaves are up to 8 x 3.5 inches in size. The aromatic foliage is glossy blue-green above, silky light brown or whitish beneath.
The leaves can be used to make tea.
The small creamy white bell shaped flowers are borne in loose axilliary clusters.
They are followed by dark blue ovoid fruits, up to 0.8 inches in length, that are borne on red stems.
The bark is red-brown and deeply furrowed.
Hardy zone 7 to 10 ( reported as hardy to -3 F though trees of southern Delaware origin may be more hardy ). The newly introduced Redbay Ambrosia Beetle is wiping out stands in the southern U.S. It bores holes in the trunk and stems, introducing a wilt disease they rapidly kills the tree.

* photo taken on March 28 2010 @ U.S. National Arboretum, D.C.

* photo taken on 4th of July 2010 @ U.S. National Arboretum, D.C.

* photos taken on June 23 2013 @ U.S. National Arboretum, DC

* photos taken on July 11 2014 in Washington, DC

* historic archive photo

Persea dothiei
A large evergreen tree reaching up to 80 feet that is native to the Himalayas at elevations up to 10 000 feet. It may possibly be adapted for used as an ornamental tree is parts of coastal central to northern California.
Hardy north to zone 8

Persea humilis ( Silk Bay )
An evergreen, upright, rounded, evergreen, small to medium-sized tree closely related to Persea borbonia, that is native to low sandy woods and swamp edges in central Florida where it is rare. Some records include: largest on record - 41 x 40 feet with a trunk diameter of 21 inches.
The elliptical leaves, up to 4 x 1.2 ( rarely over 3 ) inches, are deep green above, chestnut brown felted beneath. The very attractive, aromatic foliage has a tropical appearance..
The fruits are very similar to Persea borbonia but are borne on a longer stalk.
The red-brown bark is smooth at first, later becoming furrowed.
Hardy zones 8 to 10 in full sun or part shade on either loam or sandy soil. It is both tolerant of drought and flooding.

Persea ichangensis
A very vigorous medium size, upright, evergreen tree reaching a maximum size of 82 feet that is native to central and western China.
The attractive lance shape leaves are up to 10 x 1.5 inches in size.
Black berries, up to 0.3 inches across follow the white to yellowish-green flowers that are borne in panicles up to 4 inches in length. The flower panicles are borne in groups of 6 within a larger inflorescence.
Little known in cultivation but has been recorded in England though likely prefers hotter summers.
Hardy ones 7 to 8; it thrives especially well in the Pacific Northwest from Vancouver into Oregon. It prefers partial shade under tall conifers on moist, moderately acidic, well drained soil.

Persea indica
A medium size tree native to the Canary Island. Some records include: fastest recorded growth rate - 3 feet; largest on record - 107 ( rarely over 70 ) feet.
The leathery deep green leaves are up to 10 x 4 inches in size.
The flowers are borne in clusters up to 6 inches in length.
The fruits, up to 10 inches in length are blue-black.
Hardy north to zone 10

Persea japonica
A large evergreen tree reaching up to 66 feet or more, that is native to Korea and southern Japan.
The leaves are up to 8 x 2 inches.
Hardy north to zone 7

Persea lingue
A beautiful, rapid growing, columnar, large evergreen tree native to southern Chile. Some records include: largest on record - 133 x 50 feet with a trunk diameter of 3.5 feet.
The oval leaves are up to 5 x 2.5 inches in size.
The white flowers are borne in late spring. They are later followed by very showy olive-like fruits.
Hardiness has not been fully tested however it may grow well in the coastal regions of the western U.S. from San Francisco north to Alaska, tolerating as low as -20 F though not persistent hard freezes. It does not grow in the hot humid eastern U.S.

* historic archive photo

Persea palustris ( Swamp Bay )
A slender evergreen tree very closely related to Persea borbonia but differing in having densely hairy twigs. It also grows to about the same size as Persea borbonea. It is native to moist to swampy forests in the southern U.S. ( from eastern Texas to central Alabama to Delaware; south to the Gulf Coast and southern Florida ).
The leaves are very similar however the fruits are borne on much longer stalks than Persea borbonea.
Hardy zone 7 to 9.

* photo taken @ U.S. Botanical Garden, Wash., DC on Aug 25 2014

* photos taken on Aug 24 2017 @ U.S. Botanic Garden, Wash. DC.

* historic archive photo

Persea schiedeana
A lesser known Avocado, also with edible commerical nuts that is native to the mountains from southern Mexico to Panama at elevations of 4600 to 6200 feet. It is a very large tree. Some records include: largest on record - 170 feet.
The leaves are up to 12 x 6 inches.
It is not a tropical tree like Persea americana, instead it prefers climates that in the U.S. are only found around San Francisco.

Persea thunbergii ( Tabu Laurel or Japanese Machilus )
Also called Machilis thunbergii. A fast growing, broad-crowned, large, evergreen timber tree native to eastern China, Korea, central and southern Japan. Some records include: fastest recorded growth rate - 3 feet; largest on record - 120 x 60 ( rarely over 80 ) feet with a trunk diameter of 11.5 feet. Very long-lived, it is known to survive for as long as 1500 years. It makes an excellent shade tree in the U.S as far north as southeast Virginia and Birmingham, Alabama.
The thick, smooth-edged, oval, leaves are up to 6 x 2.7 inches in size. The foliage is reddish at first turning to glossy deep green above, whitish beneath.
The yellowish-green flowers appear late spring into early summer.
They are followed by small purplish-black fruits, up to 0.3 inches wide.
The rough bark is brownish-gray.
Hardy zones 7 to 9 ( possibly 6 on sheltered sites though more testing is needed ) in full sun to partial shade on just about any moist, well drained soil. Tolerant of salt spray. Prefers hot humid summers and thrives in the Deep South of the U.S..

* historic archive photos

Persea yunnanensis
Also called Persea bracteata & Machilis yunnanensis. An extremely attractive, long lived, ascending dome-shaped, large, evergreen tree native to the Himalayas and China in western, northwest and central Yunnan as well as Sichuan. Some records include: largest on record - 100 feet with a trunk diameter of 2.8 feet.
The thick willowy leaves are up to 8.5 x 1.6 inches in size. The very attractive foliage looks like silver swords when emerging later turning to matt to glossy deep blue-green above and striking silvery-blue beneath. The leaves are made even more attractive by the contrasting yellow midrib.
The late spring light yellow flowers are borne in clusters up to 5.5 inches in length.
They are followed by fleshy black black berries up to 0.3 inches across.
Hardy zones 7 to 8 ( tolerating 0 F ); it thrives especially well in the Pacific Northwest from Vancouver into Oregon. Drought tolerant.


Nothaphoebe cavaleriei
A fast growing, evergreen, large shrub to small tree, reaching a maximum height of 50 ( rarely over 20 ) feet. It is native to evergreen forests in northeast Yunnan as well as Sichuan in China.
The alternately-arranged, oblanceolate leaves are up to 7 x 2 inches in size. The attractive, leathery foliage is glossy deep green above, greenish-white beneath.
The tiny yellowish-white flowers appear during early summer.
The rounded, blue fruits, up to 0.6 inches wide, ripen during early autumn.
Hardy zones 7 to 9 ( some seed source is much less cold hardy ) and thrives in the humid southeastern U.S.

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