from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An allelopathic aromatic compound found in the leaves, roots, husks, and bark of plants in the Juglandaceae family, particularly the black walnut, used as a colouring agent.
from the GNU version of the Collaborative International Dictionary of English
- n. A yellow crystalline substance (C10H6O3) resembling quinone, extracted from green shucks of the walnut (Juglans regia); -- called also nucin. Chemically, it is 5-hydroxy-1,4-naphthalenedione.
from The Century Dictionary and Cyclopedia
- n. A yellowish- or brownish-red compound, HOC10H5O2. prepared by the oxidation of a-hydrojuglone from the green parts of the walnut-tree; a-hydroxynaphthoquinone, nucin, or regianin. It crystallizes in needles or prisms and melts at 151–154° C.
There is a plant toxin called juglone that is exuded from the roots of the walnut that affects surrounding plants.
But photosynthesis in the living leaves produces an ether called juglone, which evaporates into the air on warm days and can affect your brain, so you shouldn’t sleep under a walnut tree by day.
Known as "juglone" this poison is secreted by walnut roots, which can extend 50 feet from the trunk of a mature walnut tree.
Once the canopy of an orchard has closed, the trees themselves, which hate competition, secrete their own organic weedkiller, juglone, from their leaves.
There is a walnut tree just on the other side that may be affecting what grows close by with its juglone.
A knowledge of the physiology of juglone in the walnut is essential to an understanding of the divergent results obtained by various experimenters.
Brissemoret and Michaud (1917) reported the use of juglone in clinical cases for the cure of eczema, psoriasis, impetigo and other skin diseases and concluded that juglone deserves extensive use in dermatology.
The author is familiar with one case in which pure juglone was applied to a persistent ringworm infection.
Laboratory and field tests have shown juglone to be an excellent fungicide
Further the relative amounts of juglone in various species of _Juglans_ has not been completely investigated.
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