Raceme




This article is about the botanical term. For mixtures of chiral compounds in chemistry, see Racemates.





A raceme (/reɪˈsiːm/ or /rəˈsiːm/) is an unbranched, indeterminate type of inflorescence bearing pedicellate flowers (flowers having short floral stalks called pedicels) along its axis.[1] In botany, an axis means a shoot, in this case one bearing the flowers. In indeterminate inflorescence-like racemes, the oldest flowers are borne towards the base and new flowers are produced as the shoot grows, with no predetermined growth limit.[2] A plant that flowers on a showy raceme may have this reflected in its scientific name, e.g. Cimicifuga racemosa. A compound raceme, also called a panicle, has a branching main axis.[3] Examples of racemes occur on mustard (genus Brassica) and radish (genus Raphanus) plants.[3]




Contents






  • 1 Spike


  • 2 Catkin


  • 3 Spadix


  • 4 Examples


  • 5 Derivation


  • 6 See also


  • 7 References





Spike


A spike is an unbranched, indeterminate inflorescence, similar to a raceme, but bearing sessile flowers (sessile flowers are attached directly, without stalks).[2] Examples occur on Malabar nut (Justicia adhatoda) and chaff flowers (genus Achyranthes).[3] A spikelet can refer to a small spike, although it is primarily used to refer to the ultimate flower cluster unit in grasses (family Poaceae) and sedges (family Cyperaceae),[2] in which case the stalk supporting the cluster becomes the pedicel. A true spikelet comprises one or more florets enclosed by two glumes (sterile bracts), with flowers and glumes arranged in two opposite rows along the spikelet.[3] Examples occur on rice (species Oryza sativa) and wheat (genus Triticum), both grasses.[3]



Catkin


A ament or catkin is very similar to a spike or raceme, "but with subtending bracts so conspicuous as to conceal the flowers until pollination, as in the pussy–willow, alder, [and] birch...".[4] These are sometimes called amentaceous plants.[4]



Spadix


A spadix is a form of spike in which the florets are densely crowded along a fleshy axis, and enclosed by one or more large, brightly–colored bracts called spathes.[3] Usually the female flowers grow at the base, and male flowers grow above.[3] They are a characteristic of the Araceae family, for example jack–in–the–pulpit (species Arisaema triphyllum) and wild calla (genus Calla).[4]



Examples






  • A raceme





  • A spike





  • A spadix





  • The inflorescence of Spathoglottis plicata, a terrestrial orchid, is a typical raceme







  • Tightly packed raceme of Xeronema callistemon, with prominent red stamens







  • Every radiating unit in this inflorescence of a Cyperus sedge is a spikelet composed of small flowers (florets) arranged in two ranks






Derivation


From classical Latin racemus, cluster of grapes.[5]



See also



  • Inflorescence

  • Glossary of botanical terms



References





  1. ^ Walters, Dirk R.; Keil, David J. (1 January 1996). Vascular Plant Taxonomy (4th ed.). United States: Kendall/Hunt Publishing Company. p. 602. ISBN 978-0-7872-2108-9..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}


  2. ^ abc Wofford, B. Eugene (1989). Guide to the Vascular Plants of the Blue Ridge. University of Georgia Press. pp. 10–15. ISBN 978-0-8203-2455-5.


  3. ^ abcdefg Kumar, Vinay; Bhatia, S. S. (2013). Complete Biology for Medical College Entrance Examination. McGraw Hill Education Series (3rd ed.). McGraw Hill Education (India) Private Limited. p. 218. ISBN 978-1-259-06430-2.


  4. ^ abc Gilman, Daniel Coit., ed. (1907). The new international encyclopædia. 10. Peck, Harry Thurston; Colby, Frank Moore. New York: Dodd, Mead and Company. p. 618.


  5. ^ Oxford English Dictionary. Raceme 2. Bot. A type of inflorescence in which the flowers are arranged on short, nearly equal, lateral pedicels, at equal distances along a single elongated axis














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