Chrysantemum frutescens Leaves ( 1 ) : simple or compound. Alternate or whorled. Stems : (2) Generally herbaceous. Flowers : Gathered in heads, (3), similar to a single flower but being in fact an inflorescence. heads are formed by a base where single flower stand. It is called the receptacle. All around the heads there are the bracts, calyx-like, forming altogether the involucre, (4) Calyx : Transformed in a single ring of hairs or scales, parachute- like. Sometimes not present. Corolla : With 5 united petals. It can be : - Bell- shaped, ending in 5 teeth. This kind of flowers are called florets. (5) - A tube-like that opens quickly in a flat form 5 teeth ending. They are called ligules. (6) Heads can be formed: - Only by florets: (Gnaphalium decurrens) (Santolina chamaecyparissus) - Only by ligules: ( Taraxacum officinale) - with ligules outside and florets inside: (Chrysantemum frutescens)     Stamens : 5 atached at the base of the corolla, united athe the anthers like a tub,wherein style can be found. Ovary : Inferior Style : 1, with two stigmas.       Fruit: Achenes

GÈNERES There are about 900 genera. The most important : ACHILLEA ADENOSTYLES AETHEORHRIZA AMBROSIA ANACYCLUS ANDRYALA ANTENNARIA ANTHEMIS APOSERIS ARCTIUM ARCTOTHECA ARNICA ARNOSERIS ARTEMISIA ASTER ASTERISCUS ATRACTYLIS BACCHARIS BALSAMITA BELLIS BELLIUM BIDENS BOMBYCILAENA CALENDULA CARDUNCELLUS CARDUUS CARLINA CARPESIUM CARTHAMUS CATANANCHE CENTAUREA CHAMAEMELUM CHAMOMILLA CHEIROLOPUS CHONDRILLA CICERBITA CICHORIUM CIRSIUM CLADANTHUS CNICUS COLEOSTEPHUS CONYZA COTULA CREPIS CRUPINA CRYSANTHEMUM CYANOPSIS CYNARA DITTRICHIA DORONICUM ECHINOPS ECLIPTA ERIGERON EUPATORIUM EVAX FILAGINELLA FILAGO GALACTITES GALINSOGA GAMOCHAETA GLOSSOPAPPUS GNAPHALIUM GUIZOTIA GYMNOSTYLES HEDYPNOIS HELIANTHUS HELICHRYSUM HETERANTHEMIS HIERACIUM HISPIDELLA HOMOGYNE HYMENOSTEMMA HYOSERIS IFLOGA JASONIA JURINEA KOELPINIA LACTUCA LAPSANA LASIOPOGON LAUNANEA LEONTODON LEONTOPODIUM LEPIDOPHORUM LEUCANTHEMOPSIS LEUCANTHEMUM LEUZEA LEYSERA LOGFIA MANTISALCA MATRICARIA MICROPUS MYCELIS NEOLLETIA NOTOBASIS OMALOTHECA ONOPORDUM OTANTHUS OTOSPERMUM PALLENIS PETASITES PHAGNALON PHALACROCARPUM PICNOMON PICRIS PRENANTHES PROLONGOA PTILOSTEMON PULICARIA REICHARDIA RHAGADIOLUS ROTHMALERIA SANTOLINA SAUSSUREA SCHKUHARIA SCOLYMUS SCORZONERA SENECIO SERRATULA SILYBUM SOLIDAGO SOLIVA SONCHUS STAEHELINA TAGETES TANACETUM TARAXACUM TOLPIS TRAGOPOGON TRYMNUS TUSSILAGO UROSPERMUM VOLUTARIA XANTHIUM XERANTHEMUM