How did the watermelon get its common name?
The C. lanatus produces a fruit that is about 93% water, making it the majority of it water, hence the name “water” melon. The “melon” part came from the fact that the fruit is large and round and has a sweet, pulpy flesh.
Citrullus lanatus...what does that even mean?
The scientific name of the watermelon derived from both Greek and Latin roots. The Citrullus part comes from a Greek word “citrus” which is a reference to the fruit. The lanatus part is Latin, and has the meaning of being wooly, referring to the small hairs on the stems and leaves of the plant. 

Scientific Classification

Watermelon flower, permission by Forest and Kim Starr, permission by Forest and Kim Starr

      Domain- Eukarya
      Kingdom- Plantae
      Phylum- Embryophyta
      Class- Dicotyledoneae
      Order: Cucurbitales
      Family: Cucurbitaceae
      Genus: Citrullus
      Species: C. lanatus

 Domain: Eukarya
The domain Eukarya contains cells with true nuclei, as well as membrane bound organelles. These factors qualify it as a eukaryotic organism. This domain covers a gigantic variety of organisms ranging from uni-cellular protists to large animals such as the orangutan.
Kingdom: Plantae
Plantae is the kingdom with multi-cellular organisms that have cells with cell walls made of cellulose. Cells also have chloroplasts allowing them to photosynthesize, meaning they gain nutrition by energy from sunlight and water. Plantae is a kingdom that includes a wide variety of organisms as well. Another organism within this kingdom is much larger than the Citrullus lanatus and goes by the common name, the white willow.
Watermelon flower, permission by Forest and Kim Starr Embryophyta
The Citrullus lanatus is under the phylum Embryophyta because it is a land plant, located terrestrially. In addition, it contains seeds, also known as embryos. Another common organism from this phylum includes the cabbage palm.
Class: Dicotyledoneae
The class Dicotyledoneae has all vascular plants; and more specifically dicots, meaning their seeds typically has two outer shell coverings.
Order: Cucurbitales
Cucurbitales is the order containing flowering plants unisexual flowers.   
Family: CucurbitaceaeWatermelon flower, permission by Forest and Kim Starr

The family Cucurbitaceae has plants with sprawling herbaceous vines and melons. A melon is a large fruit with a fleshy inside and hard, protective skin. This family is also known as the gourd family. Other members within this family include the cantaloupe, squash, and pumpkin

Genus: Citrullus

The Citrullus lanatus is under the genus Citrullus because it is a desert vine and native to Eurasia and Africa. The flowers are yellow and the seeds are somewhat flattened. This genus contains a total of 4 species including
C. colocynthis, C. ecirrhosus, C. lanatus
, and C. rehmii.
Species: C. lanatus
The watermelon is given the name lanatus because of its pink/red or yellow flesh and black seeds, along with all of the above characteristics.

Piece of watermelon, photo taken by Johanna FischerWatermelon, permission by Forest and Kim Starr, permission by Forest and Kim Starr, photo was used with permission with some rights reserved, URL:, used with permission with some rights reserved, URL:


Below is a phylogenetic tree, demonstrating the broad classification of the Citrullus lanatus
Phylogenetic tree: Dicotyledoneae
Information modified from Campbell and Reece, Biology textbook 8th edition
The above phylogenetic tree is based off of morphological features. It is a very general classification which starts out as broad as the domains and leads into the class where the Citrullus lanatus resides.  The three domains of life include Archaea, Eukarya, and Bacteria. As explained above, the Citrullus lanatus belongs under the group Eukarya, which is broken down into 5 super-groups. Archaeplastida is the super-group land plants fall under and is ultimately where the kingdom Plantae comes from. The land plants are broken down into 4 groups, angiosperm being the type of plant of the Citrullus lanatus. Finally, the Angiosperm phylum is broken down into 3 classes: Monocodyledones, Dicotyledoneaes, and Magnoliids. Again, from the classification information above, the Citrullus lanatus is part of the Dicotyledoneaes class for evidential reasons.

Here is another phylogenetic tree representing a closer look at the family of the watermelon: Cucurbitaceae
Cucurbitaceae phylogenetic tree created by Elise Montesinos
Information modified from myetymology
This phylogenetic tree is much more specific than the first one as it morphologically compares the Citrullus lanatus  to other members within its family, Cucurbitaceae. The family Cucurbitaceae is made up of two subfamilies: Zanoioideae and Cucurbitoideae. The sub-family Cucurbitoideae is made up of all food producing plants. It has 7 “tribes” including the one the Citrullus lanatus falls under called the Benincaseae. There are 12 genera members of this tribe, Citrullus  being one of them. Finally, like stated above, the genus Citrullus contains 4 species, including lanatus, also known as, the watermelon.

Find out where in the world you can find the Citrullus lanatus under habitat/geography!