Tubular flower

Tubular flowers in the flower head of the black-eyed rudbeckia

As tubular flowers (including disc florets ) refers to generally radial (aktinomorphe) single flowers in scheinblütigen flower heads of the daisy family (Asteraceae). Tubular flowers are usually hermaphroditic. More rarely, they are purely female, purely male, or sterile (sterile).

In the representatives of the subfamily Asteroideae , the almost always hermaphrodite tubular flowers stand close to the center of the flower head. At the edge they are surrounded by larger ray florets , which are purely female or sterile and attract pollinating insects.

In the subfamily Carduoideae , the cups consist only of tubular flowers. In some taxa (for example in the knapweed ) the tubular flowers on the edge can be more or less zygomorphic and enlarged; these flowers with a lock function are mostly sterile.

A two-lipped formation of the Corolla is rarely possible, as in the tribe of the Mutisieae or in the subfamily of the Barnadesioideae and in the Pectis .

In the subfamily of the Cichorioideae , the flower heads only contain ray-flowers.

Structure of a tubular flower

Structure of a tubular flower; here without pappus, with a completely reduced calyx:
A. ovary
B. corolla tube
C.
fused anthers tube D. two-branch pistil

The tubular flowers can stand on the base of the cup in the axilla of reduced bracts , which are called chaff scales (palea). The calyx is transformed into a pappus , it consists of bristles, hair or scales or it can also be completely reduced. The three or five fused petals usually have only short petal lobes , while the corolla tube is long and narrow, which means that they have a long tubular shape overall. The three to five stamens are fused with the crown at the base and form a stamen-corolla tube . They have free stamens and are fused together on the anthers. The flowers are usually protandrisch (formerly male), the stylus grows through the anthers tube and pushes out the pollen with "puffy hairs" that are on the outside or the tip of the stylus (secondary pollen presentation). Only then does it unfold its two scar branches . The ovary is inferior, unilocular and consists of two carpels with an ovule and basal placentation . The fruit is an achenes (Cypsela) or, very rarely, a stone fruit (in Chrysanthemoides ).

Flower head of the daisy .
Inside there are yellow tubular flowers, on the edge the white ray-flowers
Close-up of tubular flowers from jewelry cups
With the Carduoideae; here the felt burdock , the flower heads are composed only of tubular flowers
Flower baskets of the mountain knapweed made only of tubular flowers, with sterile, enlarged tubular flowers on the edge

Some representatives of the nightshade , primrose and gentian families also have petals that have grown together to form a tube, so that their flowers are sometimes referred to as tubular flowers.

literature

Peter H. Raven, Ray F. Evert, Helena Curtis: Biology of plants. Walter de Gruyter, Berlin 1985, ISBN 3-11-007446-X , p. 412.
Peter Sitte, Hubert Ziegler, Friedrich Ehrendorfer, Andreas Bresinsky: Strasburger, textbook of botany. Gustav Fischer, Stuttgart, Jena, New York 1991, ISBN 3-437-20447-5 , pp. 809-810.
Asteraceae (PDF), from Plantz Africa - SANBI, accessed on June 1, 2018.
Nádia Roque, David J. Keil, Alfonso Susanna: Illustrated glossary of Compositae. 2009, in: VA Funk u. a .: Systematics, evolution, and biogeography of Compositae. International Association for Plant Taxonomy, University of Vienna, 2009, ISBN 978-3-9501754-3-1 , Appendix A, online (PDF) at researchgate.net, accessed June 1, 2018.
James W. Byng: The Flowering Plants Handbook. Plant Gateway, 2014, ISBN 978-0-9929993-0-8 , p. 501.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f Peter H. Raven, Ray F. Evert, Helena Curtis: Biology of Plants. Walter de Gruyter, Berlin 1985, ISBN 3-11-007446-X , p. 412.
↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Peter Sitte, Hubert Ziegler, Friedrich Ehrendorfer, Andreas Bresinsky: Strasburger, textbook of botany. Gustav Fischer, Stuttgart, Jena, New York 1991, ISBN 3-437-20447-5 , p. 809.
^ ^A ^b ^c ^d Eckehart J. Jäger: Rothmaler excursion flora from Germany. Vascular plants: baseline. Spektrum, Heidelberg 2011, ISBN 978-3-8274-1606-3 , p. 774.
↑ Nádia Roque, David J. Keil, Alfonso Susanna: Illustrated glossary of Compositae.
^ Peter Sitte, Hubert Ziegler, Friedrich Ehrendorfer, Andreas Bresinsky: Strasburger, textbook of botany. Gustav Fischer, Stuttgart, Jena, New York 1991, ISBN 3-437-20447-5 , p. 810.

[Raven-1] ↑ ^a ^b ^c ^d ^e ^f Peter H. Raven, Ray F. Evert, Helena Curtis: Biology of Plants. Walter de Gruyter, Berlin 1985, ISBN 3-11-007446-X , p. 412.

[Sitte-2] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Peter Sitte, Hubert Ziegler, Friedrich Ehrendorfer, Andreas Bresinsky: Strasburger, textbook of botany. Gustav Fischer, Stuttgart, Jena, New York 1991, ISBN 3-437-20447-5 , p. 809.

[Rothmaler-3] A ^b ^c ^d Eckehart J. Jäger: Rothmaler excursion flora from Germany. Vascular plants: baseline. Spektrum, Heidelberg 2011, ISBN 978-3-8274-1606-3 , p. 774.

[4] Nádia Roque, David J. Keil, Alfonso Susanna: Illustrated glossary of Compositae.

[Sitte2-5] Peter Sitte, Hubert Ziegler, Friedrich Ehrendorfer, Andreas Bresinsky: Strasburger, textbook of botany. Gustav Fischer, Stuttgart, Jena, New York 1991, ISBN 3-437-20447-5 , p. 810.