8.4: Inflorescence Types

Last updated
Save as PDF

Page ID: 35352

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

Spathe & Spadix

The spathe of a Calla lily — Figure \(\PageIndex{1}\): In the image on the left, the spathe is shown wrapped around and enclosing the spadix (not visible). The spathe on a Calla lily looks like one large, funnel-shaped, white petal. In the image on the right, the top of the spadix is shown. This part of the spadix is covered with the male florets, making pollen. Photos by Maria Morrow, CC BY-NC.

The top of a Calla lily spadix — Figure \(\PageIndex{1}\): In the image on the left, the spathe is shown wrapped around and enclosing the spadix (not visible). The spathe on a Calla lily looks like one large, funnel-shaped, white petal. In the image on the right, the top of the spadix is shown. This part of the spadix is covered with the male florets, making pollen. Photos by Maria Morrow, CC BY-NC.

The base of a Calla lily spadix — Figure \(\PageIndex{2}\): This is the base of the Calla lily spadix. It is covered with female florets. The gynoecium is shaped like a bowling pin, each with a large knob-like stigma at the top. Photo by Maria Morrow, CC BY-NC.

Head (also called a composite or capitulum)

Head inflorescence with pollinators — Figure \(\PageIndex{3}\): A dandelion head inflorescence. Each "petal" is actually composed of five fused petals of a single floret. The tube-like structures emerging upward are the styles, each with two curled stigma lobes. Because this inflorescence has no disc flowers, it is called a ligulate head. Photo by Maria Morrow, CC BY-NC.

A head inflorescence with two floret types — Figure \(\PageIndex{4}\): This oxeye daisy has a head inflorescence with two types of florets. In the center, there are yellow disc florets. These have five short petals and radial symmetry. Lining the outside of the inflorescence are white ray florets. These have several petals fused together in one long strap-like, bilaterally symmetrical corolla. The image on the right shows the bracts lining the outside of the inflorescence, called phyllaries. People commonly mistake these as sepals when considering this inflorescence as a single flower. Photos by Maria Morrow, CC BY-NC.

The phyllaries of the head inflorescence in the previous picture — Figure \(\PageIndex{4}\): This oxeye daisy has a head inflorescence with two types of florets. In the center, there are yellow disc florets. These have five short petals and radial symmetry. Lining the outside of the inflorescence are white ray florets. These have several petals fused together in one long strap-like, bilaterally symmetrical corolla. The image on the right shows the bracts lining the outside of the inflorescence, called phyllaries. People commonly mistake these as sepals when considering this inflorescence as a single flower. Photos by Maria Morrow, CC BY-NC.

A clover head inflorescence — Figure \(\PageIndex{5}\): Clovers are quite beautiful, particularly up close. The fuzzy ball it produces is composed of many bilaterally symmetrical florets, typical of the flower morphology found in the legume family. These florets all attach to the same receptacle. Can you locate the calyx and corolla of each floret? Photo by Maria Morrow, CC BY-NC.

Spike

A Plantago inflorescence — Figure \(\PageIndex{6}\): This *Plantago* inflorescence is a wind-pollinated spike. The florets have no showy perianth. The prominent structures seen here are the large anthers, located at the end of long, thin filaments. These florets are sessile, attached directly to the peduncle with no pedicels. Photos by Maria Morrow, CC BY-NC.

Raceme

Catkin

Umbel

A green peduncle transitions into a spray of smaller pedicels, each with a purple floret at the end. — Figure \(\PageIndex{9}\): In an umbel, the pedicels all emerge from the top of the peduncle. The *Allium cernuum* inflorescence on the right is a drooping umbel. Drawing by Pearson Scott Foresman, Public domain, via Wikimedia Commons. Photo on the right by Steve Ganley, CC-BY-NC.

An umbel inflorescence where each pedicel has its own umbo of tiny white florets — Figure \(\PageIndex{10}\): A compound umbel is when each pedicel then forms its own umbel. Drawing by H.M. Dixon, Public domain, via Wikimedia Commons. Photo of *Aegopodium podagraria* by Сергей, CC-BY-NC.