Dahlia (UK /deɪliə/ or US /dɑːliə/) is a genus of bushy, tuberous, herbaceous perennial plants native to Mexico. A member of the Asteraceae (or Compositae), dicotyledonous plants, related species include the sunflower, daisy,chrysanthemum, and zinnia. There are 42 species of dahlia, with hybrids commonly grown as garden plants. Flower forms are variable, with one head per stem; these can be as small as 5 cm (2 in) diameter or up to 30 cm (1 ft) ("dinner plate"). This great variety results from dahlias being octoploids—that is, they have eight sets of homologous chromosomes, whereas most plants have only two. In addition, dahlias also contain many transposons—genetic pieces that move from place to place upon an allele—which contributes to their manifesting such great diversity.
The stems are leafy, ranging in height from as low as 30 cm (12 in) to more than 1.8–2.4 m (6–8 ft). The majority of species do not produce scented flowers or cultivars. Like most plants that do not attract pollinating insects through scent, they are brightly colored, displaying most hues, with the exception of blue.
The dahlia was declared the national flower of Mexico in 1963. The tubers were grown as a food crop by the Aztecs, but this use largely died out after the Spanish Conquest. Attempts to introduce the tubers as a food crop in Europe were unsuccessful
Rudbeckia /rʌdˈbɛkiə/ is a plant genus in the sunflower family. The species are commonly called coneflowers and black-eyed-susans; all are native to North America and many species are cultivated in gardens for their showy yellow or gold flower heads.
The species are herbaceous, mostly perennial plants (some annual or biennial) growing to 0.5–3 m tall, with simple or branched stems. The leaves are spirally arranged, entire to deeply lobed, 5–25 cm long. The flowers are produced in daisy-like inflorescences, with yellow or orange florets arranged in a prominent, cone-shaped head; "cone-shaped" because the ray florets tend to point out and down (are decumbent) as the flower head opens.
A large number of species have been proposed within Rudbeckia, but most are now regarded as synonyms of the limited list given below.
Several currently accepted species have several accepted varieties. Some of them (for example the Black-eyed Susan, R. hirta), are popular garden flowers distinguished for their long flowering times. There are many cultivars of these species.
Rudbeckia species are eaten by the caterpillars of some Lepidoptera species including Cabbage Moth and Dot Moth.
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My name is Jonathan and I enjoy working in my garden in my spare time. I am no professional, just an amateur. My second love is photography, shooting the flowers in my garden and of course sharing them with people who share my passions.