Starr 080531-4851 Chamaesyce hypericifolia

''Chamaesyce'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of plants in the family Euphorbiaceae. Recent

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

studies have shown that ''Chamaesyce'' is deeply nested within the broader '' Euphorbia''. 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 '' Euphorbia''. 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 exactly 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 all ...

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 A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

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 (sometimes called a pseudanthium, 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 (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...

or a single

pistil Gynoecium (; ) 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 of a flower; it consists of (one or more) ''pistils'' ...

without

petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...

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 The term ''sepalum'' was coined b ...

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

s plus the

gynoecium Gynoecium (; ) 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 of a flower; it consists of (one or more) ''pistils'' ...

of a single flower, actually form an inflorescence surrounded with many staminate flowers surrounding a single

pistillate flower This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

. 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 An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

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

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...

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, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...

s (collectively called the involucre),

adapted In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...

leaves attached below the cyathium. These bracts are fused into a cup-like structure. In some species, such as ''Chamaesyce 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