Sunflower (0)

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The sunflower (Helianthus annuus) is an annual(iga aastane) plant in the family
Asteraceae, with a large flower head (inflorescence(õiekobar, õisik, õitseaeg, õidumine)).
The stem(tüvi) of the flower can grow up to 3 metres tall, with the flower head reaching
30 cm in diameter. The term "sunflower" is also used to refer(nimetama, viitama, üle
andma) to all plants of the genus(perekond, sugu) Helianthus, many of which are
perennial(alaline, aastaringne) plants.
What is usually called the flower is actually a head (formally(ametlikult) composite(liit-,
komposiit- ; korvõieline, komposiit) flower) of numerous flowers (florets)
crowded(täistuubitud, tunglev, rahvarohke) together. The outer flowers are the ray
florets(pähik (õisiku osa) and can be yellow, maroon, orange, or other colors, and are
sterile(steriilne, viljatu). The florets inside the circular head are called disc florets.

Sunflower head displaying florets in spirals of 34 and 55 around the outside
The florets within this cluster(kobar, kimp, klaster, parv ; kobarasse kogunema) are
arranged (korraldatud, ettekavatsetud)spirally(spiraalselt). Typically each floret is
oriented(suunitlusega) toward(poole) the next by approximately(umbkaudu, ligikaudu)
the golden angle(parima nurga alla), producing a pattern(muster, lõikeleht,
seaduspärasus) of interconnecting spirals where the number of left spirals and the number
of right spirals are successive Fibonacci numbers.(fibonacci arv/ rida) Typically, there are
34 spirals in 1 direction(suund, juhatamine, juhis) and 55 in the other; on a very large
sunflower you may see 89 in one direction and 144 in the other.
The disc florets mature(täiskasvanud ; valmima, kääritama ) into what are traditionally
called "sunflower seeds", but are actually the fruit (an achene) of the plant. The true
seeds are encased(ümbritsetud, koorikus) in an inedible husk (söögikõlbmatu,
mittesöödav, kest, aganad ; kroovima, koorima)
Heliotropism (heliotropism (taime päikese poole pöördumine)
Sunflowers in the bud(pung, õienupp ; tärkama, punguma) stage exhibit(välja panema,
näitama ; eksponaat, asitõend) heliotropism. At sunrise, the faces of most sunflowers are
turned towards the east. Over the course(kurss, suund, kulg, kursus, käik, väljak,
müürilade) of the day, they move to track(jälitama) the sun from east to west, while at
night they return to an eastward(ida suunaline, ida poole) orientation. This
motion(liikumine, esildis) is performed by motor cells in the pulvinus, a flexible
segment(segment, lõik ; segmenteerima, tükeldama) of the stem just below the bud. As
the bud stage ends, the stem(tüvi) stiffens(kangestuma, jäigastuma) and the blooming
stage is reached.
Sunflowers in the blooming stage are not heliotropic anymore. The stem has frozen,
typically in an eastward orientation. The stem and leaves lose their green color.
The wild sunflower typically does not turn toward the sun; its flowering heads may face
many directions when mature. However, the leaves typically exhibit some heliotropism.
Cultivation and uses

A sunflower farm near Mysore, India.

Sunflower heads solds as snacks in China.
Sunflowers are native(pärit) to the Americas. The earliest known examples of a fully
domesticated sunflower were found at the Olmec site of San Andrés dating some time
95% sisust ei kuvatud. Kogu dokumendi sisu näed kui laed faili alla
Sunflower #1 Sunflower #2 Sunflower #3 Sunflower #4 Sunflower #5 Sunflower #6 Sunflower #7 Sunflower #8 Sunflower #9 Sunflower #10 Sunflower #11 Sunflower #12 Sunflower #13 Sunflower #14 Sunflower #15 Sunflower #16 Sunflower #17 Sunflower #18 Sunflower #19 Sunflower #20 Sunflower #21 Sunflower #22 Sunflower #23 Sunflower #24 Sunflower #25 Sunflower #26 Sunflower #27 Sunflower #28 Sunflower #29 Sunflower #30 Sunflower #31
50 punkti Autor soovib selle materjali allalaadimise eest saada 50 punkti.
~ 31 lehte Lehekülgede arv dokumendis
2010-04-01 Kuupäev, millal dokument üles laeti
13 laadimist Kokku alla laetud
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kollane00 Õppematerjali autor

Lisainfo

inglise keelne referaat päevalillest
päevalill , kasvatamise kultuur , haigused

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