The Commoner's Botanical Guide to Nuts

... for the next time some smart vegan from Richmond tells you that peanuts are not really botanical nuts. 

Botanists are the hippies among scientists, but like all scientists they've created their own little world of code language and lunacy.

Botanically a nut is a type of fruit. The seed of the fruit is covered by a layer, and that layer is called pericarp. It is divided into three layers: endocarp, mesocarp, and exocarp. In nuts all three layers have morphed together into one hard, dry, woody layer. Most nuts "commonly referred to as" nuts, aren't nuts. Of course, it's controversial which nut is really a nut as many nuts cannot be clearly categorized. 

Real information here.  

I've added the German names of the "nuts", as well as the type of fruit (like "drupe" or "nut" or "capsule") in German, so you can also mock the Germans in Mayfair and beyond.

walnut


German: Walnuss
Juglans regia
is a drupe (stone fruit) - only the endocarp is hard.

German: Steinfrucht
pecan
 
German: Pekannuss
Carya illinoinensis
is a drupe.
German: Steinfrucht
peanut
 
German: Erdnuss
Arachis hypogaea
is a legume.

German: Hülsenfrucht
Brazil nut
German: Paranuss (after the Brazilian city of Para)
Bertholletia excelsa
is a capsule ("capsule fruit").
German: Kapselfrucht
hemp seeds
German: Hanfsamen
Cannabis sativa
is an achene, which is a special kind of nut.
German: Achaene
soy nuts
German: "Sojanüsse" (geröstete Sojabohnen)
Glycine max
are soya beans. Soya is a legume.
German: Hülsenfrucht
hazel nut
German: Haselnuss
Corylus avellana
is a true nut. It's the nut of nuts.
German: Nussfrucht
almond
German: Mandel
Prunus amygdalus
is a drupe.
German: Steinfrucht
coconut
German: Kokosnuss
Cocos nucifera
is a drupe. The coconut is the king of drupes.
German: Steinfrucht
cashew nut



German: Cashewnuss
Anacardium occidentale
is a drupe. The "cashew nut" is the fruit. The cashew apple is not a fruit, it's an accessory fruit, it's a thickened stem.
German: Steinfrucht
pistachio
German: Pistazie
Pistacia vera
is a drupe.
German: Steinfrucht
sunflower seed
German: Sonnenblumenkern
Helianthus annuus
is a type of achene, so it's a nut.
German: Achaene
wheat
German: Weizen
Triticum
is a grain. Grains are the fruits of grasses. Grains are caryopses. A caryopsis is another special case of a nut.
German: Karyopse
macadamia
German: Macadamianuss
Macadamia
is a follicle fruit.
German: Balgfrucht
pine nuts
German: Pinienkern
Pinus
are the seeds of pine trees, and they come from pine cones. They are not even fruits. Pines have "naked seeds" without a fruit covering the seeds.
German: Samen (= seed)
chestnut
German: Esskastanie
Castanea sativa
is a true nut. But nutritionally it's not a nut.
German: Nussfrucht
acorn
German: Eichel (be aware that in German "Eichel" also refers to the glans of the penis, and "glans" is also what some botanists call this particular type of nut in English.)
Quercus
is a true nut. The acorn itself, not the little "hat" is the nut. Nutritionally it's not a nut.
German: Nussfrucht 
kola nut
German: Kolanuss 
Cola
is a true nut. 
German: Nussfrucht
Chilean hazelnut
German: chilenische Haselnuss 
Gevuina avellana
is a drupe.
German: Steinfrucht
buckwheat
German: Buchweizen
Fagopyrum esculentum
is an achene, which is a special kind of nut.
German: Achaene
strawberry seeds

German: Erdbeersamen ("Erdbeere" is strawberry. Also be aware that the German "Samen" which means "seed", when it stands alone unlike here also means "semen".
Fragaria
The small seeds on strawberries are achenes, so they are the nuts, i.e. they are the fruits. The red strawberry itself is not a fruit. It's an accessory fruit ( a "fake fruit"), it's "extra tissue".
German: Sammelnussfrucht
corn (maize)
German: Mais
Zea mays
is a grain, so it's a caryopsis, so it's a nut.
German: Karyopse
rice

German: Reis
Oryza sativa
is a caryopsis, so it's a nut.
German: Karyopse
beechnut
German: Buchecker
Fagus sylvatica
is a true nut, but not nutritionally.
German: Nussfrucht
tigernut (chufa nut)
German: Erdmandel 
Cyperus esculentus
is a tuber, not a fruit. They grow underground.
German: Knolle
rosehip
German: Hagebutte
Rosa canina
The rosehip seeds are achenes. So they are nuts.
German: Achaene
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