Bear River Walnut Ranch/Gilbert Group Walnuts

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Bear River Walnut Ranch is situated in the fertile alluvial fan of the Bear River. The area has a historic link to both the Gold Rush, in that much of the ranch's soil is the product of hydraulic mining, and to some of the earliest large-scale agriculture in California, the Durst Hop Farms. Below you will find information about walnuts: their evolutionary history, their domestication, and their currently known health benefits. Walnuts have a very low ecological profile and tend to be perceived as improving the ambiance of an agricultural area, much like grapes or apples, due to the shade they provide, the local summertime temperature reduction they promote via broad-leaf evapotranspiration, and the aromatic oils they emit around harvest time.

Walnuts evolved to be mammal food, and this likely explains their high nutritive value. Explore the links below to learn about the evolutionary origins of walnuts and how they came to be one of the world's healthiest purely natural food supplements.

Genus Juglans, the Walnut species of the world
Fruits, Seeds, & Nectar

©2022 the Gilbert Family


Figure 1.Wild Juglans world distribution. Light blue is the projected distribution of walnuts prior to the time of the Persian and Greek empires, although it is uncertain if the actual pre-empire native distribution is more to the east, closer to that of Juglans sigilata (dark blue). ©Bear River Walnut Ranch


The ‘rosids’

More than a quarter of all angiosperms and are 'rosids' (Wang et. al, 2009). Because of the rapidity of the rosid radiation in the Middle and Late Cretaceous, many of the deep evolutionary relationships of the group are difficult to precisely reconstruct. In other words, new groups of rosids were arising, proliferating, changing form, competing, and sometimes going extinct at a very rapid pace in the Cretaceous as evolution tinkered with the manifold new possibilities allowed by flowers, fruit, and pollen. Rosids are thus very diverse in form, and the group includes trees, vines, aquatic plants, parasitic plants, and small plants including all varieties of fruits, from legumes, to vegetables, to sweet fruit and nut crops. Many rosids have root nodules where symbiotic relationships with soil bacteria that promote nitrogen fixation occur, a feature that appears to be related to a major adaptive radiation (Soltis, 1999).


The rosid radiation is associated with the rise of angiosperm-dominated forests and also with the proliferation of modern ant lineages and other herbivorous or otherwise plant-dependent insect groups. Although amphibians have a very deep evolutionary history that extends into the Permian, the vast majority of amphibian species live in trees, and angiosperm forests appear to have driven several adaptive radiations of amphibians in the Cretaceous and Cenozoic (Wang et. al, 2009).



Fagales appears to have originated during the major rosid radiation in the middle Cretaceous. Fagales is characterized by dry fruit/nuts, flowers that occur in compact clusters, and roots that promote ectomycorrhizal relationships between roots and fungi which allows for incorporation of nitrogen and growth in poor soils. Often fagales forms produce flavonol compounds related to isoflavonoids and flavonoids and other complex molecules associated with mitigating a multitude of specific fungus-root relationships in the ‘rhizosphere’ (Hause, 2009); these compounds have diverse biochemical and antioxidant qualities that can provide health benefits to animals and humans.



Figure 4. Evolutionary history of Juglans ©Bear River Walnut Ranch



Juglandaceae is the walnut family, and is a closely-related clade (evolutionary group) that includes walnuts, pecans, and hickory. The fruit of Juglandacaea is technically a ‘drupe’ (drupaceous nuts), not a true nut. In a drupe an outer fleshy part and flesh surrounds a shell (pit) with a seed inside. True nuts, like hazel nuts, do not have an outer fruit layer (husk). Juglandaceae have unisexual flowers and wind dispersed pollen. Juglandaceae includes the subfamilies Engelhardioideae and Juglandoideae



Engelhardoidea, which includes Engelhardia, Oreomunnea, and Alfaroa (Blokhina, 2004), differs from Juglandoideae in the way it flowers, by pollen morphology, and by wood anatomy (Iljinskaja, 1990). Alfaroa is a non-deciduous tree from the tropical rain forest highlands of Central America. Wood retains a solid pith. Alfaroa bears small, one-chambered nuts. Engelhardia is composed of a number of species of trees across southeast Eurasia, Indonesia and the Philippines. Oreomunnea is a genus of large trees native to Mesoamerican hihgland rainforest. Oreomunnea leaves are arranged in opposite pairs, differentiating it from most members of Juglandaceae. The fruit is a small nut with a three-lobed wing.



Juglandoidea is composed of two tribes: Platycaryeae and Juglandeae. Platycaryeae comprises a single species Platycarya strobilacea, though one to two additional species are accepted by some authors. It is native to eastern Asia in China, Korea, and Japan.

References cited


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