Sketching again. #botany #placentation

Photo of a cucumber sliced in trans-section showing the three seed-bearing placentas attached around the inner wall of the fruit. Scott Zona CC BY-NC 2.0.

Placentation in the #Cucurbitaceae is parietal. The placentas are attached to the wall of the ovary & the ovules (future seeds) point inward, toward the center of the fruit. This cucumber has 3 fused carpels & 3 placentas. #placentation #PlantMorphology #Botany 🌾🧪🌱

Photo of a pomegranate cut in cross-section to reveal the 7 locules (like 7 segments in a citrus fruit) that are filled by intruded parietal placentae. The seeds are attached to the placentae.

The #placentation of pomegranate (Punica granatum; #Lythraceae) looks complex, but look closely to see the 7 locules divided by paper-thin septa. Each locule is filled by an intruded parietal placenta bearing numerous seeds (= mature ovules). 📷: Jay Peg CC BY-NC 2 #Botany #PlantScience 🌾🧪

Photo of backlit fruits of Lunaria. We can see the silhouette of the the ovules attached on long stalks (funiculi) from two parietal placentae. Scott Zona CC BY-NC 2

The placentae of #Brassicaceae are parietal, in 2 longitudinal lines. A false septum develops from the 2 placentae (& remains after the fruit dries & splits open). It is “false” because it is not vascularized & not equivalent to carpel walls. #placentation 📷: Lunaria annua #Botany #PlantScience 🌾🧪

Photo of an unripe capsule in longitudinal section. The ovules are attached to a column that rises up in the center of the locule but does not connect with the top of the locule.

This rough dissection of a Silene banksia fruit shows a single locule (chamber) with the immature seeds on a free-central placenta. The placenta is a central stalk that does not reach the top of the locule, hence “free.” #placentation #Caryophyllaceae #Botany #PlantScience 🌾🧪

Photo of a pink grapefruit cross-section. A few aborted seeds are visible in the axillary position of each section (locule).

This grapefruit (Citrus × aurantium f. aurantium) is a seedless cultivar, although some undeveloped seeds are present. We can see that the placentation type is axile (i.e., in the axils of the locules). #placentation #Rutaceae : Stefan Van der Straeten CC BY-NC-ND 2 #Botany #PlantScience 🌾🧪

Photo of a tomato cut in cross-section and back-lit. The tomato has three locules. Three massive placentae are attached in the axillary position of the three septa. The seeds are visible attached to the placentae.

This photo of tomato fruit shows a fruit with three carpels forming three locules (chambers). A large, intruding placenta (with its seeds) is clearly visible in each locule. This is axile placentation. #placentation #Solanaceae : Jo Christian Oterhals CC BY-NC-ND 2
#Botany #PlantScience 🌾🧪

Photo of two green (unripe) capsules of Iris. One is cut in cross-section. The capsule is divided into three locules by septa. The unripe seeds are attached to placentae in the axils of the three septa.

Axile placentation is very common in the plant kingdom (maybe the most common among multicarpellate families?). The placentae & ovules (→seeds) are in the axils of each carpel, as seen here in the immature tricarpellate fruits of Iris tectorum. #Iridaceae #placentation #Botany #PlantScience 🌾🧪

Photo of a cucumber with one end sliced off and a single, thin cross-section. In the cross-sectional view, one can see three placentae attached to the inside wall of the fruit. The immature seeds are still attached to the placentae. Photo by Scott Zona CC BY-NC 4.0.

You are familiar with parietal placentation (even if you don’t know it by that name). If you’ve ever sliced a #cucumber, you’ll have seen how the seeds/ovules are attached along three longitudinal placentae on the ovary wall. Cucumis sativus #Cucurbitaceae #placentation #Botany #PlantScience 🌾🧪

Figure 4.22. Diagram of placentation types showing ovaries in section, placentae, and ovules. Diagramed types are: Parietal, Parietal with intruded placenta, Parietal or Lateral, Free Central, Axile, Apical and Basal.

This week I’m posting about placentae! The position of the #placenta within the #ovary can define genera, families or sometimes even entire orders. This chart (from Judd et al. Plant Systematics: A Phylogenetic Approach, ed. 4) shows various types of #placentation. #Botany #PlantScience 🌾🧪