''Chamaesyce'' is a

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

(formerly considered a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

) of plants in the family

Euphorbiaceae Euphorbiaceae (), the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of Euphorbia, the type genus of the family. Most spurges, such as ''Euphorbia paralias'', ar ...

. Recent

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

studies have shown that ''Chamaesyce'' is deeply nested within the broader ''

Euphorbia ''Euphorbia'' is a large and diverse genus of flowering plants, commonly called spurge, in the family (biology), family Euphorbiaceae. Euphorbias range from tiny annual plants to large and long-lived trees, with perhaps the tallest being ''Eu ...

''. Specifically, ''Chamaesyce'' is very closely related to plants like '' Euphorbia pulcherrima'', the popular poinsettia (this and related plants have also been given in their own genus, ''Poinsettia'', but are also well nested within ''Euphorbia''). Currently, all species have now been reclassified as species of ''

''. Specifically, this group now belongs to ''Euphorbia'' subgenus ''Chamaesyce'' section ''Anisophyllum'' (which can be abbreviated ''Euphorbia'' sect. ''Anisophyllym''). Taxonomically speaking, ''Chamaesyce'' is considered a

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

of ''Euphorbia''. ''Euphorbia'' sect. ''Anisophyllum'' is a large group with about 365 species. ''Euphorbia'' sect. ''Anisophyllum'' differs from other ''Euphorbia'' species in a number of characteristics. Perhaps the most important is the presence of C4 photosynthesis in all but one subsection (subsection ''Acutae'', which represents a basal clade that is made up of species with intermediate C2 photosynthetic pathways). Other characteristics include sympodial branching, dorsi-ventral stems, asymmetric leaves, non-glandular stipules, and ecarunculate seeds. Chamaesyce albomarginata 2

Plants in the group (as with all other species in the genus ''Euphorbia'') bear tiny

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

ing structures that look like single true flowers, as if each one were a flower with many stamens surrounding a single ovary. In fact, the structure is a

cyathium A cyathium (: cyathia) is one of the specialised Pseudanthium, pseudanthia ("false flowers") forming the inflorescence of plants in the genus ''Euphorbia'' (Euphorbiaceae). A cyathium consists of: * Five (rarely four) bracteoles. These are sm ...

(sometimes called a

pseudanthium A pseudanthium (; : pseudanthia) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, composite flowers ...

, meaning a "false flower"). It is made up of many small flowers, but with each flower reduced to only the functional organs of sexual reproduction: a single

stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

or a single

pistil Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl (botany), whorl of a flower; it consists ...

without

petal Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corol ...

s or

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

s. Under magnification it can be seen that what appear to be many

s plus the

gynoecium Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl (botany), whorl of a flower; it consists ...

of a single flower, actually form an inflorescence surrounded with many staminate flowers surrounding a single pistillate flower. Each individual staminate flower contributes only a single stamen and retaining no other structure apart from a

vestigial Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...

stalk below the base of the stamen's

filament The word filament, which is descended from Latin ''filum'' meaning " thread", is used in English for a variety of thread-like structures, including: Astronomy * Galaxy filament, the largest known cosmic structures in the universe * Solar filament ...

. That stalk joins the

capitulum capitulum (plural capitula) may refer to: *the Latin word for chapter ** an index or list of chapters at the head of a gospel manuscript ** a short reading in the Liturgy of the Hours *** derived from which, it is the Latin for the assembly known ...

or base of the

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

— the flowering head. Similarly, what appears to be the flower's

ovary The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/ oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are end ...

is the gynoecium of a single pistillate flower that has lost all the other associated organs of a flower. What appear to be the

s of an individual flower are in fact appendages produced by glands that are produced by

bract In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also lo ...

s (collectively called the

involucre In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also look ...

), adapted leaves attached below the

. These bracts are fused into a cup-like structure. In some species, such as ''Euphorbia albomarginata'', the glandular appendages are quite showy. Starr 041223-2238 Chamaesyce celastroides

Starr 041223-2238 Chamaesyce celastroides

Starr 050222-4138 Chamaesyce hypericifolia

References

{{Taxonbar, from=Q15405502 Euphorbiaceae genera Historically recognized angiosperm genera