A young #Acacia urophylla seedling showing a good example of #Heteroblasty with its juvenile true leaves, and the first developing mature phyllode! @scottzona.bsky.social flashback to your Heteroblasty series!!

Plate of 2 photos. Lower photo (by Luc Strydom CC BY-NC 4.0) shows a rosette of narrow, strappy leaves. Upper photo (by Carel Jongkind CC BY-NC 4.0) shows a node with a single narrowly obovate leaf with terminal paired tendril hooks.

Triphyophyllum peltatum (#Dioncophyllaceae) has rosettes of early leaves that are facultatively insect-trapping (in low P habitats) (lower 📷). Late leaves are non-carnivorous & have paired tendril hooks for climbing (upper 📷). This liana has next-level #heteroblasty! #botany 🌱🧪🌾

Plate of 2 photos. Left photo (by John Barkla CC BY 4.0) shows an unbranched shrub with drooping, narrow leaves. Right photo (by Raphael von Büren CC BY-NC 4.0) shows a tree with a branched canopy. The leaves are broader and spreading.

Another example of #heteroblasty as a possible defense against browsers: Pseudopanax crassifolius (#Araliaceae) has tough, narrow, drooping leaves initially, but later leaves are very different. Could browsing by now-extinct moas have selected for this heteroblasty? Who knows?🤷‍♂️ #botany 🌱🧪🌾

Photo of leafy shoots. Lower shoots have pale, narrow, curled leaves. Upper shoots have broad, green, elliptical leaves.

Terminalia bentzoe subsp. rodriguesensis (#Combretaceae) is a strange case of #heteroblasty: lower leaves are thin & look dead. The upper leaves are broad & green. Did this evolve as a defense against browsing by the now-extinct saddle-backed giant tortoise (Cylindraspis vosmaeri)? #Botany 🌱🌾🧪

Photo of two severed shoots. The lower nodes bear opposite, lobed leaves. Upper nodes bear opposite entire leaves. Scott Zona CC BY-NC 2.0.

Shoots of Lonicera japonica (#Caprifoliaceae) emerge from underground, overwintering buds bearing lobed leaves. As they continue to grow they switch to unlobed leaves. Nobody knows why. 🤷‍♂️ It’s a strange example of #heteroblasty. #botany 🌱🧪🌾

Photo of a shrub with palmately compound leaves with fine-textured, narrow leaflets.

Photo of palmately compound leaves with broad leaflets.

Here’s how I learned firsthand about #heteroblasty: Pleranda elegantissima (syn. Dizygotheca e., Aralia e.; #Araliaceae). Juveniles are popular houseplants. 📷1: Cazé Hélène CCBYNCSA4. Adults look very different. 📷2: Mark Richman CCBY4. #Botany 🌱🧪🌾

Photo of a tree in a rainforest. Growing up the trunk is a climbing aroid. The lower leaves are shingle-like but upper leaves are larger, have long petioles, and are not shingle-shaped. Scott Zona CC BY-NC 2.0.

Another classic case of heteroblasty is Monstera dubia (#Araceae). It starts life as a shingle-leaf climber, but as it reaches the higher light levels of the canopy, the leaves enlarge & take on adult morphology. Here it’s growing in Costa Rica. #heteroblasty #Shingleleaf #botany 🌱🧪🌾

Note that the leaf change does not necessarily coincide with sexual maturity, thus the terms “juvenile” and “adult” (as I used in my earlier #heteroblasty post) are misleading. We use those terms out of convenience. Heteroblasty is uncoupled from sexual maturity.

Photo of a tree seedling. There are pinnately compound leaves with ovate leaflets, but a shoot in the center bears sickle-shaped phyllodes.

A classic example of #heteroblasty is the switch from leaves to phyllodes (flattened, photosynthetic petioles). You can see the abrupt change in Acacia auriculiformis (#Fabaceae): pinnate leaves give way to sickle-shaped phyllodes. 📷: jayeshpatil912 CCBY2 #Botany 🌾🧪🌱

Photo of a tree with ivy growing up the trunk. A hand holds a non-climbing branch with unlobed ovate leaves and flowers—the adult morphology of ivy. Scott Zona CC BY-NC 2.0.

Heteroblasty is an abrupt (not gradual) change in the morphology of the plant during development. A common type of heteroblasty is seen in juvenile vs adult shoots in Hedera helix (Araliaceae). I’m holding an adult shoot against the juvenile climber. #heteroblasty #Botany 🌾🧪🌱