science

Sempervivoideae

Sempervivoideae is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Sempervivoideae rather than just read about it. In short: Sempervivoideae is the largest of three subfamilies in the Saxifragales family Crassulaceae, with about 20–30 genera with succulent leaves. Unlike the two smaller subfamilies, it is distributed in temperate climates.

Key takeaways

Sempervivoideae belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Sempervivoideae to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sempervivoideae from memory before moving on to harder problems.

Reference excerpt

Sempervivoideae is the largest of three subfamilies in the Saxifragales family Crassulaceae, with about 20–30 genera with succulent leaves. Unlike the two smaller subfamilies, it is distributed in temperate climates. The largest genus in this subfamily is Sedum, with about 470 species.

Description Succulent leaved plants. Unlike the other two smaller subfamilies, which are highly derived, Sempervivoideae retain the basic features of the family Crassulaceae. The Sempervivoideae contain many familiar horticultural plants, such as Sedum.

Taxonomy Sempervivoideae has taxonomic priority over its synonym, Sedoideae, and is related to the other Crassulaceae subfamilies, as shown in this cladogram, although Messerschmid and colleagues (2020) state that these three subfamily clades are successive sisters, rather than Sempervivoideae being a direct sister only to Kalanchoideae.

Subdivisions Six clades within the Subfamily Sempervivoideae have been segregated into five tribes with about thirty genera.

The composition of the five tribes are: (number of genera/species);

Telephieae (6/50) Umbiliceae (4/100) Semperviveae (2/75) Aeonieae (3/70) Sedeae (7/520) and their relationship is shown in the cladogram:

However, given the difficulty of establishing a stable classification, some authors prefer larger groupings, e.g.;

Telephinae (Telephieae, Umbilicieae) Sedinae (Semperviveae, Aeonieae, Sedeae) Alternatively, Messerschmid and colleagues (2020), based on the largest analysis of subfamily taxa, propose the following clade structure (with tribes) and number of genera, species;

Telephium (Telephieae, Umbiliceae) 9, 160 Sempervivum (Semperviveae) 3, 60 Aeonium (Aeonieae) 4, 67 (+ Sedum p.p. 8 sp.) Leucosedum (Sedeae p.p.) 6,80 (+ Sedum p.p. 120 sp.) Acre (Sedeae p.p.) 7, 205 (+ Sedum p.p. 345 sp.) In this analysis, these clades and tribes were related as shown in this cladogram;

Semperviviae, Aeonieae and Sedeae are definable only by plesiomorphic features, with their genera all derived from within Sedum. Segregates of Sedum occur in each of these, but lack sufficient features to allow them to be allocated to definitive genera.

Genera

Many of the genera in this subfamily have been considered non-monophyletic. Other than the Sempervivum clade, Sedum has never formed a monophyletic group, but rather is scattered through the remaining clades, and thus is highly polyphyletic (or paraphyletic). This has been referred to as the "Sedum problem". Given the monophyly demonstrated for Aeonieae and Semperviveae (as quite distinct from Sedeae), it has been recommended that those species of Sedum originally found in those tribes, be removed from the genus and reassigned. This includes Sedum series Rupestria from Semperviveae, but collectively account for only a small fraction of the genus. While restricting Sedum to Sedeae simplifies the infrafamilial structure of the genus, its species remain distributed within both clades of this tribe. Sedum, with about 470 species, is by far the largest (and most problematic) genus within the subfamily, and the family Crassulaceae.

Evolution and biogeography There is no known fossil record of Crassulaceae. The Crassulaceae family evolved approximately 100 million years ago (mya) in southern Africa with the two most basal phylogenetic branches (Crassula, Kalanchoe) representing the predominantly southern African members. Divergence times are shown in Cladogram III. The family had a gradual evolution, with a basal split between Crassuloideae and the rest of the family (Kalanchoideae, Sempervivoideae) at 82 mya, and Sempervivoideae splitting from Kalanchoideae at 71 mya. The Sempervivoideae subsequently dispersed north to the Mediterranean region, and from there to Eastern Europe and Asia (Sempervivum and Leucosedum clades), with multiple groups spreading over the three continents of the Northern Hemisphere. The Telephium clade splitting from the rest of the subfamily at 66 mya. This was followed by the Petrosedum and Aeonium clades at 56 mya and Sempervivum/Jovibarda at 52 mya. The remaining two clades, constituting Sedeae (Leucosedum and Acre) separating from each other at 48 mya. Two lineages from the European Crassulaceae eventually dispersed to North America and underwent subsequent diversification. The Aeonium clade dispersed from northern Africa to adjacent Macaronesia.

Notes

References

Bibliography

External links Media related to Sempervivoideae at Wikimedia Commons Data related to Sempervivoideae at Wikispecies

Illustrations

Worked examples

Example 1 — a first encounter with Sempervivoideae

Start with the simplest possible case. Write down what Sempervivoideae claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sempervivoideae before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sempervivoideae ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sempervivoideae

In research: Sempervivoideae appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Sempervivoideae in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Sempervivoideae is common in secondary-school and first-year university syllabi. It links to neighbouring topics Crassulaceae, Eudicot subfamilies, so understanding it makes those chapters shorter.
In everyday life: Look for Sempervivoideae outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Sempervivoideae in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Sempervivoideae means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Sempervivoideae out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sempervivoideae in simple terms?

Why does Sempervivoideae matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sempervivoideae?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sempervivoideae.