Sunday, July 26, 2015

Persea americana - Avocado

The avocado is a really common sight here in SC county. They are medium sided trees forming an upright to eventually an oval to rounded form with age. Still, 30' is way too tall to easily harvest the fruit. This is the iconic tree at Shoppers Corner. Tough spot for a large tree, surrounded by asphalt, compaction and heat.



Foliage is more or less evergreen dropping leaves at flowering, simple, alternate, 4-8" long, elliptical to ovate to oval, with entire margins, glossy dark green upper surface, lighter or whitish below, though in the spring new foliage can be tinged red. Old leaves falling in early spring.




Blooming late winter to early spring, the yellowish green flowers are tiny produced in large quantities on an upright airy panicle, individual flowers lack petals but have perianth lobes (?).



Flowers are pretty normal looking but have some interesting blooming patterns. All the flowers open as females first, saying open for only several hours and then close up for a day or longer and then open up with males shedding pollen. There are two distinct flowering types, called A and B. With "A" types the flowers open as females in the morning and become males in the afternoon of the second day. The "B" types open as females in the afternoon and then as males the following morning. So, what does that mean or do for them? It means that for maximum fertilization, you should have more than one tree. But in cooler conditions the flower sequence is slowed allowing for more self fertilization.
Our local experts, Four Winds Nursery, say that in our climate they seem to flower differently, and there is no need for cross pollination.



Fruit is a fleshy drupe or a berry depending on your reference, and called both by the Royal Horticulture Society. The single large seed is surrounded by an oily flesh and a very thin skin. Different varieties can be large or small (3-13" long) firm or soft at maturity, green skin or dark, smooth to rough, round to pear shaped. I learned years ago, prior to studying botany, that the seed influences the flesh as we made guacamole and it oxidized quickly if you didn't put the seed in it.



Stems are thick, green during the first year, browning soon into the second year.



Bark is beautiful on older trees, gray brown with deep fissures.




I recall driving north from San Diego years ago on the "Avocado" highway. I also remember as a kid back in the early 60's a good friend of my dad's looking to cash in on the speculation of the Avocado boom. Seems the guy was always chasing the next big thing and lost.


Misidentification:
Not sure?

Location:
Santa Cruz
Shoppers Corner parking lot