Thursday, September 24, 2020

Plant Profile: Yucca filifera

Latin name: Yucca filifera ("YOU-kah fill-IFF-er-ah")
Common name: Mexican Tree Yucca, Palma China, Chinese palm
Originally from: Chihuahua desert in North-Eastern Mexico.
Blooms: An unusual 5' long weeping panicle of white bell-like flowers pollinated by moths and butterflies.
Light: Full sun.
Water: Winter rain is enough - hates waterlogged roots.
Height x width: 25' x 8'
Zones: 7b to 10b
Where to find in P. Garden: We have three at the top of at PG and half a dozen in two groups down at PRG.

Yucca filifera was discovered in the 1840’s in North-Eastern Mexico by explorer Josiah Gregg. It was introduced to Europe in the 1870’s. I hadn't seen these for sale until last year at Flora Grubb gardens, where I immediately pounced on one to try it out.

Since then I have bought or been given about 10 more, because they are so incredibly tough, architectural and easy to grow. Deer resistant? Allegedly. Human resistant? For sure!

A common plant in North-Eastern Mexico, and in Mexico as a whole, it is found at altitudes of 1400-7800', in areas with an annual rainfall of around 11-24". Yucca filifera grows in a huge variety of environments, and can be seen in huge forests at the foot of mountains in deep soils, in desert-scrub, grassland, thorn-scrub and occasionally in oak or pinyon-juniper woodland.

With rigid, narrow leaves, 1.5" wide and 18" long arranged around the trunk, the plant looks like Yucca aloifolia except with thin white threadlike leaf margins: the name filifera is from Latin ‘filim’ meaning thread; and ‘fera’ meaning carrying.

Yucca filifera is a tall branching evergreen tree that, in 20-50 years, can reach 25-40' tall with a spread of 8-15'. The trunk usually branches at around 10-14' and can develop a massive and wide base when old. They only seem to be available in a 5 gallon single stemmed size at retail and wholesalers, though I have tried to get larger ones - no luck.

As with many tough and common plants, they have a lot of uses. Indigenous people used the leaves of Yucca filifera as a roof covering and as a source of fiber for handcrafting. The flowers, fruit and stem can be eaten raw or cooked and the flower spike cooked and eaten like asparagus. Yucca filifera can also be dried and crushed for use as a flavoring, though I've no idea what it would taste like.

The root contains saponins which are not toxic, but they are difficult for the human body to digest. Plants containing saponins can be crushed in water to create a foam so were often used for cleaning.

Saponins in general have a number of potential, modern day medicinal applications as they are found to exhibit anti-inflammatory and immune-boosting properties and have antibacterial effects. They are thought to help reduce cholesterol levels, kill bacteria, and inhibit tumor growth.

On the whole this is a super xeric garden plant and I highly recommend it.


Monday, September 21, 2020

It's a great time to plant agaves

Summer has given way to fall, but if you've lived in the Bay area for long you'll know now is the driest time of year. The gardens are parched and the ground is dusty dry, and we have watered a few plants (new tree Aloes, and a palm we planted) but some plants love the heat. Agave is one genus that thinks the hotter the better!

We did have some weird weather recently that some agaves didn't love though. A hot dry spell, followed by foggy, smoke-laden air, leads to some agaves ending up with edema scarring. 

These mottled marks on some leaves are caused by water being pulled up to the leaves during hot weather, but stopping in its tracks when cool, humid weather hits. The cells loaded with water then burst and scar the leaves. Unfortunate, but the plants will eventually grow new leaves.

We had a lovely September volunteer day, with Chris, Josh, Matt, Hilary, John and Andrea generating 18 bags of green waste for recycling! We got lots of plants cut back (the cardoon, salvias, euphorbias and so on) and turned and watered the compost.

We also planted some great agaves that Matt and I have been growing. Josh put in three Agave maximiliana... or they might be Agave zebra. Except both of these species are supposed to be solitary and this one pups like mad...We will just have to wait and see what they turn into.

Josh also planted a group of seven Agave desmettiana variegates behind the wrong way sign. That area has become a huge farm for baby agaves but we hope to reorganize the plants, put them in groups, and make something pretty out of it all soon.

Matt and I visited with the famous Brian Kemble of the Ruth Bancroft Gardens the following week, and had a blast weeding his pots of hybrid Agaves, Aloes and Gasterias while talking about all the cool plants he has grown and known. 

 In exchange he gave us some lovely plants for the garden, including three Aloe polyphylla hybrids which we planted right away on the lower pathway where they will hopefully thrive. Matt added five more Agave desmettiana variegates in that area too, as well as a few on the way to the tool trunk.

A week later Matt and I were back at the garden, planting yet more Agaves we have been growing on at home. We did two groups of Agave gypsophylla up in the top area of PG, and a group of three Yucca aloifolia "Magenta Magic" down at PRG.

It's great to get some plants out of our home garden and into the public gardens - it can take years to grow something big enough to plant out in a street park (small plants tend to get stolen, or crushed) and I feel now that 3-5 gallons is the minimum if possible.

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