February 1, 2023
Rhus Glabra

In this journey of ours through life, it is amazing how many varieties of plants we encounter just walking down the street. And when you research them it is amazing what you find. For example, Rhus glabra which I came across yesterday on my walk. It is also known as Scarlet Sumach, Upland, Pennsylvania Sumach, Vinegar Tree, or Smooth Sumach. Of course Sumach, Sumaq, besides being a shrub or a family of plants is a well-known spice that is actually derived from the dried fruits of some species of Rhus. Not this one!

The spice Sumach is derived from the dried fruits of Rhus coriaria. It is a sour reddish-purple powder used especially in middle-eastern cuisine. You might also see it sprinkled on Hummus and Tashi. It is an ingredient in falafel and Persians added it to their Chelo-Kabab. However, in North America, Rhus glabra is used to make a beverage tasting similar to lemonade.

Poisonous species of Rhus:

You can distinguish the non-poisonous varieties by observing their fruit which is clothed with acid crimson hairs, with compound, dense panicles. The poisonous species have smooth fruits and axillary panicles. Some well-known poisonous species include Rhus Toxicodendron or Poison Ivy, Rhus diversiloba or Poison Oak, and Rhus vernix or Poison Sumach. All three contain a substance called urushiol which causes an allergic reaction in humans.

Rhus Glabra
Came across Rhus Glabra in London, UK

I came across this tree when it is in bloom and hopefully in the near future I will get to see the fruits! All these years, I had no idea where this spice originates from.

This variety originates in North America and it is hardy, it can tolerate frosts down -20°C of -4°F. It is a clump-forming, deciduous shrub that produces and propagates through suckers. Rhus glabra belongs to the Anacardiaceae family of plants. Rhus glabra has grayish bark and bluish-green pinnate leaves. The flowers are yellowish-green. The shrub blooms in early summer. In autumn Rhus glabra leaves turn nice shades of yellow and red.

How to grow Rhus glabra:

Grow Rhus glabra in full sun and in well-drained, soil. It tolerates most types of soils. Rhus glabra can grow up to 2.5m or 8ft.

Rhus glabra can grow very wide in fact it could be as wide as it is high. Therefore, you can prune this tree each year to maintain its shape. You can also propagate this shrub, by wood cuttings or root cuttings in autumn.

Rhus Glabra

Rhus glabra fruit:

This shrub comes in male and female fruits will only appear on the female plants. Rhus glabra produces fruits in autumn. They are reddish in color and they hang in clusters. They are covered in a crimson down that is very sour to the taste, as it contains malic acid. To preserve their acidity, they should be picked before rain or water touches them.

Due to the high content of tannins, they use the leaves in the tanning of leather. They use the bark for dyes. They use this plant in medicines.

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