Hawthorn, Valerian, Chamomile and the Plants Weiss Wrote About

Table of Contents

1. A Physician’s Medicine Chest of Plants
2. Hawthorn: The Heart Herb
3. What the Hawthorn Trials Found
4. Valerian: Sleep and the Problem of Measuring It
5. Chamomile: Constituents and Clinical Trials
6. Bitters: Gentian, Wormwood and Digestion
7. Cough Teas and Mild Remedies
8. Rauwolfia and the Strong Plant Drugs
9. St John’s Wort and Milk Thistle in German Practice
10. Strengths and Limits of the Evidence
11. Key Research Papers
12. Connections

1. A Physician’s Medicine Chest of Plants

Weiss came to plant medicine twice over. As a boy in Berlin he was already absorbed in botany, and as a young man he wrote two doctoral theses at once — one in medicine, one on the plants growing on the gypsum hills of the southern Harz. He then trained as an internist at the Charité. His plants were therefore never a folk collection kept apart from “real” medicine. In the words his colleagues later quoted from the preface to his first book, he wanted knowledge of medicinal plants drawn from “observing nature” but always applied on “the ground of clinical medicine”.

Two habits run through everything he published on individual plants. The first was to ask how a plant works — the title of his 1963 paper on hawthorn is literally “The mechanism of action of Crataegus oxyacantha”. The second was to sort plant drugs by the strength of their action. According to a tribute by his colleague K.-Ch. Schimmel, Weiss demanded that medicinal plants be classified into forte (strong) and mite (mild) phytotherapeutics, and that natural plant substances be distinguished from isolated pure compounds. No source fetched for this page lists which plants he placed in which group, so no assignments are made in his name here; the classification itself is described on the Lehrbuch der Phytotherapie page.

What can be said in general pharmacological terms is that the two ends of the scale look very different. At the strong end sit plants such as foxglove, whose isolated glycosides are dosed in fractions of a milligram and which William Withering brought into medicine in 1785. At the mild end sit everyday teas such as chamomile and peppermint, which are drunk by the cupful and whose effects are gentle enough that measuring them reliably is itself a scientific problem. Most of the plants below fall somewhere along that line.

From the 1950s to the 1970s Weiss published a long series of review papers in the German journal Hippokrates, organised by disease rather than by plant: phytotherapy of rheumatoid arthritis, of colitis, of arteriosclerosis, of cough, and a paper on medicinal plants in prevention. The plant-specific papers he wrote in that series and in Planta Medica provide the framework for the sections that follow.

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2. Hawthorn: The Heart Herb

Hawthorn (Crataegus, including the species Weiss named in his title, C. oxyacantha, now usually grouped with C. laevigata and C. monogyna) is the thorny hedgerow shrub of European fields. Its berries, leaves and flowers have a long history as a heart remedy. The pharmacognosist Franz-C. Czygan, who co-edited the Zeitschrift für Phytotherapie with Weiss from 1980, wrote a short cultural history of hawthorn “as a cardiac agent” in 2005, tracing how a hedge plant became one of the central heart herbs of German medicine.

What Weiss wrote

Weiss’s 1963 paper “The mechanism of action of Crataegus oxycantha” appeared in Hippokrates. PubMed holds the title but no abstract, so its arguments are not summarised here. It sits beside his 1957 review on the phytotherapy of arteriosclerosis in the same journal. The title alone shows the direction of his interest: not simply that hawthorn was used for the heart, but how it might act.

Constituents

Hawthorn leaf and flower contain oligomeric procyanidins (chains of flavan-3-ol units), flavonoids such as vitexin, hyperoside, rutin and quercetin, and triterpene acids such as ursolic and oleanolic acid. The site’s Hawthorn page describes these groups and the effects on heart contraction and blood-vessel tone studied in the laboratory. The standardized extracts used in modern trials are usually prepared from leaf with flower and standardized to their procyanidin or flavonoid content.

Its official standing

Hawthorn is one of the clearest examples of a traditional plant that passed into formal regulation. Germany’s Commission E, the expert committee on which Weiss sat, approved hawthorn leaf with flower for heart failure of New York Heart Association (NYHA) stage II — the stage at which ordinary activity brings on symptoms. A 2005 review by B. Steinhoff set the hawthorn monographs of the European Pharmacopoeia, Commission E, the European Scientific Cooperative on Phytotherapy (ESCOP) and the World Health Organization side by side. The regulatory story itself is told on the Commission E page.

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3. What the Hawthorn Trials Found

The most-cited summary of the modern evidence is the Cochrane review by Pittler, Guo and Ernst (2008), “Hawthorn extract for treating chronic heart failure”. It found 14 randomized, double-blind, placebo-controlled trials. In most of them hawthorn extract was given as an addition to standard heart-failure treatment, not instead of it.

• Pooled data: 10 trials with 855 patients could be combined for meta-analysis.
• Exercise: compared with placebo, hawthorn extract improved maximal workload and exercise tolerance.
• Heart work: the pressure–heart-rate product, an index of how hard the heart is working, improved.
• Symptoms: shortness of breath and fatigue improved more with hawthorn than with placebo.
• Survival: there were no mortality data apart from one trial, which reported 3 deaths in the hawthorn group and 1 in the control group — far too few to show an effect either way.
• Side effects: adverse events were infrequent, mild and transient.

The reviewers concluded that hawthorn extract gives a significant benefit in symptom control and physiological outcomes as an adjunct treatment for chronic heart failure. What the review could not answer is the question that matters most in heart failure — whether people live longer. The trials were small and mostly short, and all used standardized extracts, so their results apply to those preparations rather than to hawthorn teas or berry products. The site’s Heart Failure page describes the condition and its conventional treatment, and its History page tells the foxglove story that forms the other half of plant medicine for the heart.

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4. Valerian: Sleep and the Problem of Measuring It

Valerian (Valeriana officinalis) is a tall meadow plant with pale pink flowers and a strong-smelling root. The root has been used as a calming and sleep remedy in Europe since antiquity, and in twentieth-century Germany it became one of the standard plant medicines for restlessness and poor sleep, often combined with hops or lemon balm.

Constituents

The root contains an essential oil, valerenic acid and related sesquiterpenes, and unstable compounds called valepotriates. Valerenic acid is the most studied: laboratory work links it to the brain’s GABA system, the main calming signal network, which the site’s Valerian page describes in more detail. Because the composition of a root extract depends on the plant, the solvent and the storage, two “valerian” products can differ considerably.

Three meta-analyses that disagree

Valerian is a textbook case of how the same body of trials can be read in different ways.

• Bent and colleagues (2006) pooled 16 randomized trials with 1,093 patients. Most trials had methodological problems. When sleep quality was scored simply as improved or not improved, people taking valerian were more likely to report improvement (relative risk 1.8, 95% confidence interval 1.2–2.9), but the authors found evidence of publication bias — small negative trials may never have been published.
• Fernández-San-Martín and colleagues (2010) analysed 18 randomized placebo-controlled trials. They found no significant difference in the time taken to fall asleep (a pooled difference of 0.70 minutes) or in quantitative measures of sleep quality. People on valerian were somewhat more likely to report feeling better (relative risk 1.37), and the authors concluded that valerian’s effectiveness “has not been demonstrated with quantitative or objective measurements”.
• Shinjyo, Waddell and Green (2020) reviewed 60 studies and pooled 10 of them (1,065 people) on subjective sleep quality. They suggested that the inconsistent results of earlier trials may come from the variable quality of herbal extracts, reported no severe adverse events in people aged 7 to 80, and concluded that valerian could be a safe and effective herb to promote sleep.

The disagreement is mainly about measurement. People often say they sleep better on valerian, while sleep-laboratory measures and timed sleep onset show little or no change. Whether that gap reflects a real benefit that instruments miss, a placebo response, or publication bias is exactly what the three reviews read differently.

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5. Chamomile: Constituents and Clinical Trials

German chamomile (Matricaria recutita, also called Matricaria chamomilla) is a small daisy-like plant of fields and roadsides. In the German tradition it was the all-purpose household remedy: a tea for an upset stomach and cramps, a steam inhalation for colds, a rinse for the mouth and skin, and a calming drink at night. Weiss was writing in a country where Kamillentee was in practically every kitchen; the site’s Chamomile page covers the plant and its uses in full.

Constituents

A 2010 review by Srivastava, Shankar and Gupta described chamomile’s two main groups of active compounds: terpenoids and flavonoids. Among the terpenoids are alpha-bisabolol and chamazulene, the compound that colours the distilled oil deep blue; among the flavonoids is apigenin, which has been studied for its effects on the nervous system. The same review summarised chamomile’s traditional uses for inflammation, digestive complaints, anxiety and sleep.

The anxiety trials

For all its long use, chamomile reached rigorous clinical testing late.

• Amsterdam and colleagues (2009) ran what they described as the first randomized, double-blind, placebo-controlled trial of an oral chamomile extract in generalized anxiety disorder, with 57 patients. Anxiety scores on the Hamilton Anxiety Rating Scale fell more with chamomile than with placebo (P = 0.047). The authors described the result as “modest anxiolytic activity”.
• Mao and colleagues (2016) tested chamomile over the long term. People who had responded to chamomile were randomly assigned to continue it or switch to placebo; 93 were randomized. The risk of relapse was lower with chamomile but the difference was not statistically significant (hazard ratio 0.52, P = 0.16), while anxiety symptoms over the follow-up were significantly lower in the chamomile group.

Taken together, the trials point to a small effect, in small samples, using a standardized extract rather than tea. That fits the picture of chamomile as a mild remedy in the older German sense: unlikely to cause harm, unlikely to produce dramatic results, and therefore hard to study.

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6. Bitters: Gentian, Wormwood and Digestion

The bitters — Amara in the old pharmacy Latin — are plants whose main medicinal property is an intensely bitter taste. For centuries European physicians gave them before meals for poor appetite, sluggish digestion and convalescence. The traditional explanation is that bitter taste on the tongue triggers a reflex increase in saliva, stomach acid and digestive juices.

What Weiss wrote

In 1966 Weiss published “Die Amara in der heutigen Therapie” (“Bitters in present-day therapy”) in a supplement of Planta Medica. No abstract is available, so the paper’s content is not summarised here; its title shows that he regarded the bitters as part of current medicine rather than a relic.

Gentian

Yellow gentian (Gentiana lutea), an alpine plant with a thick root, is the classic bitter. According to the pharmacy handbooks cited on the site’s Gentian page, the root contains 2 to 8% bitter substances, mostly secoiridoid glycosides. The main one is gentiopicroside; a smaller amount of amarogentin, one of the most bitter natural compounds known, accounts for much of the taste.

Wormwood

Wormwood (Artemisia absinthium) is the other great European bitter, and the source of absinthe. Its bitterness comes from compounds such as absinthin, but its essential oil also contains thujone, a nerve toxin that can trigger seizures at high doses — a hazard the site’s Wormwood page describes. Wormwood is a reminder that “bitter tonic” and “harmless” are not the same thing. Milder bitter-tasting plants used in the same tradition include dandelion root.

Modern clinical trials of bitters for digestion are few; most of the evidence remains traditional or experimental, and the site’s individual herb pages report what has been tested.

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7. Cough Teas and Mild Remedies

Herbal cough teas were a staple of German pharmacies and households throughout Weiss’s career. Traditional blends draw on a small set of plants with different supposed roles: thyme, whose oil contains thymol (first isolated from thyme oil in 1719); marshmallow root, whose slippery mucilage coats an irritated throat; licorice root; and aromatic seeds such as fennel and anise. Peppermint and echinacea belong to the same everyday cold-season shelf.

What Weiss wrote

In 1961 Weiss published “Antitussive teas and other antitussive plant drugs” in Hippokrates. As with his other papers of the period, PubMed lists the title without an abstract, and its specific contents are not reproduced here. The topic shows how seriously he took the humble tea: a cough tea was, to him, a plant drug worth reviewing in a medical journal.

The problem of the mild remedy

Mild remedies raise a particular question for research. In a 2000 paper, V. Schulz argued that in conditions such as depression the psychological part of a treatment’s effect can outweigh its pharmacological part, so that a simple drug-versus-placebo comparison may understate the value of a gentle, well-tolerated remedy. That is Schulz’s argument, not a settled conclusion, but it explains why plants such as chamomile and the cough-tea herbs often show small or uncertain results in trials despite their long popularity. Licorice, too, shows that a “mild” tea plant can carry real effects: the site’s Licorice pages describe its effect on blood pressure and potassium with heavy use.

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8. Rauwolfia and the Strong Plant Drugs

At the other end of the scale from chamomile stands Indian snakeroot, Rauvolfia serpentina (often written Rauwolfia), a small shrub of the Indian subcontinent long used in Ayurvedic medicine. In the early 1950s its alkaloid reserpine was isolated and entered Western medicine as a treatment for high blood pressure and, for a time, for severe psychiatric illness. It is one of the best-known examples of a modern drug taken directly from a traditional plant remedy.

Reserpine works by emptying nerve endings of their stores of the chemical messengers noradrenaline, serotonin and dopamine. That made it a powerful research tool — the brain-chemistry work described on the Katz, von Euler and Axelrod and Carlsson, Greengard and Kandel pages relied on it — and it also explains its best-known drawback: depression was reported in some people treated with it.

What Weiss wrote

In 1958, while reserpine was still new, Weiss published “The present status of the Rauwolfia problem” in Hippokrates. Again, only the title is indexed. Its existence shows him following one of the most important plant-derived drugs of his time as it happened.

Strong plant drugs in general

Rauwolfia belongs with foxglove, opium, belladonna and ergot among the plants whose effects are so strong that medicine eventually replaced the crude plant with a purified, precisely dosed compound. This is the distinction between natural plant substances and isolated pure compounds that Weiss insisted on. Plant medicine in his sense included both kinds; the history of the purified compounds is told across the site’s Pharmacology section, from Dioscorides onward.

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9. St John’s Wort and Milk Thistle in German Practice

Two plants that became flagships of German herbal medicine late in Weiss’s life deserve a short note, though no fetched source records his own views on either. In a 1999 overview, H. Wagner counted more than 300 clinical studies of standardized plant medicines carried out in Germany after 1980, with Hypericum (St John’s wort) and Silybum (milk thistle) among the plants most studied, alongside hawthorn, valerian, ginkgo and echinacea.

St John’s wort

St John’s wort (Hypericum perforatum) is a yellow-flowered meadow plant that blooms around midsummer. The Cochrane review by Linde, Berner and Kriston (2008) analysed 29 trials with 5,489 patients with major depression. The extracts tested were superior to placebo and similarly effective to standard antidepressants, with fewer side effects. The reviewers also found that trials from German-speaking countries reported more favourable results than trials from elsewhere, a pattern that complicates interpretation. As the site’s St John’s Wort page describes, the plant also has one of the most extensive drug-interaction profiles of any herb: its constituent hyperforin induces the liver enzyme CYP3A4 and the transporter P-glycoprotein, which can lower blood levels of many medicines, including oral contraceptives and warfarin.

Milk thistle

Milk thistle (Silybum marianum) has a long history as a liver remedy in European medicine. In 1968 chemists at the University of Munich isolated its active complex, silymarin, giving a molecular basis to the old reputation. The site’s Milk Thistle page reports the clinical evidence for liver conditions and its limits.

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10. Strengths and Limits of the Evidence

Weiss’s stated aim was to move plant medicine from a healing art judged by experience to a therapy explained by science, and later in life, according to his colleagues, he demanded proof of action and efficacy. Measured against that aim, the plants on this page have fared very differently.

• Hawthorn: a Cochrane review of randomized trials found benefits on exercise capacity and symptoms as an add-on treatment, with mild side effects — but no usable data on survival.
• Valerian: three meta-analyses agree that people often report better sleep, but disagree on whether objective measures change; possible publication bias and variable extract quality are recognised problems.
• Chamomile: two trials show a modest effect on generalized anxiety in small samples.
• Bitters and cough teas: long traditional use and plausible mechanisms, but few modern controlled trials.
• Rauwolfia: unquestionably powerful — strong enough to become a purified prescription drug, with the side effects that strength brings.
• St John’s wort: the strongest trial base of any herb on this page, together with important drug interactions and a puzzling difference between German-language and other trials.

Several limits apply across the board. Most modern trials tested standardized extracts, so their results say little directly about home teas. Many trials were small and short. Plant products vary in composition from batch to batch. And for the mild remedies especially, the placebo-controlled trial may be a blunt instrument, as Schulz argued. The research also shows that “natural” does not mean free of effects: thujone in wormwood, depression with reserpine and the interactions of St John’s wort are all documented findings.

What Weiss left behind was less a verdict on each plant than a way of asking the question: which plant, which part, which preparation, how strong, and what does the evidence show. The Commission E and Legacy page follows how that question was turned into regulation.

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Key Research Papers

1. Weiss RF. [The mechanism of action of Crataegus oxycantha]. Hippokrates. 1963;34:602-5. PubMed PMID: 14046338
2. Weiss RF. [Contributions to phytotherapy. VII. Phytotherapy of arteriosclerosis]. Hippokrates. 1957;28(8):247-51. PubMed PMID: 13428239
3. Weiß R. Die Amara in der heutigen Therapie [Bitters in current therapy]. Planta Med. 1966;14(S 01):128-32. DOI: 10.1055/s-0028-1100090
4. Weiss RF. [Antitussive teas and other antitussive plant drugs]. Hippokrates. 1961;32:14-8. PubMed PMID: 13784093
5. Weiss RF. [The present status of the Rauwolfia problem]. Hippokrates. 1958;29(10):315-9. PubMed PMID: 13548843
6. Czygan FC. [A short cultural history in retrospect. Crataegus as a cardiac agent]. Pharm Unserer Zeit. 2005;34(1):10-3. PubMed PMID: 15700789
7. Steinhoff B. [The pharmacopoeia and Commission E of the ESCOP and the WHO. Hawthorn in the view of the monographs]. Pharm Unserer Zeit. 2005;34(1):14-21. PubMed PMID: 15700790
8. Pittler MH, Guo R, Ernst E. Hawthorn extract for treating chronic heart failure. Cochrane Database Syst Rev. 2008;2008(1):CD005312. PubMed PMID: 18254076
9. Bent S, Padula A, Moore D, Patterson M, Mehling W. Valerian for sleep: a systematic review and meta-analysis. Am J Med. 2006;119(12):1005-12. PubMed PMID: 17145239
10. Fernández-San-Martín MI, Masa-Font R, Palacios-Soler L, Sancho-Gómez P, Calbó-Caldentey C, Flores-Mateo G. Effectiveness of Valerian on insomnia: a meta-analysis of randomized placebo-controlled trials. Sleep Med. 2010;11(6):505-11. PubMed PMID: 20347389
11. Shinjyo N, Waddell G, Green J. Valerian Root in Treating Sleep Problems and Associated Disorders-A Systematic Review and Meta-Analysis. J Evid Based Integr Med. 2020;25:2515690X20967323. PubMed PMID: 33086877
12. Srivastava JK, Shankar E, Gupta S. Chamomile: A herbal medicine of the past with bright future. Mol Med Rep. 2010;3(6):895-901. PubMed PMID: 21132119
13. Amsterdam JD, Li Y, Soeller I, Rockwell K, Mao JJ, Shults J. A randomized, double-blind, placebo-controlled trial of oral Matricaria recutita (chamomile) extract therapy for generalized anxiety disorder. J Clin Psychopharmacol. 2009;29(4):378-82. PubMed PMID: 19593179
14. Mao JJ, Xie SX, Keefe JR, Soeller I, Li QS, Amsterdam JD. Long-term chamomile (Matricaria chamomilla L.) treatment for generalized anxiety disorder: A randomized clinical trial. Phytomedicine. 2016;23(14):1735-1742. PubMed PMID: 27912875
15. Linde K, Berner MM, Kriston L. St John's wort for major depression. Cochrane Database Syst Rev. 2008;2008(4):CD000448. PubMed PMID: 18843608
16. Wagner H. Phytomedicine research in Germany. Environ Health Perspect. 1999;107(10):779-81. PubMed PMID: 10504142
17. Schulz V. The psychodynamic and pharmacodynamic effects of drugs: a differentiated evaluation of the efficacy of phytotherapy. Phytomedicine. 2000;7(1):73-81. PubMed PMID: 10782494

PubMed Topic Searches

1. Crataegus (hawthorn) and heart failure
2. Valerian and sleep: meta-analyses
3. Chamomile and anxiety: randomized trials
4. Weiss RF in Hippokrates

Further Reading

• Weiss RF. Die Pflanzenheilkunde in der ärztlichen Praxis: Vorlesungen an der Berliner Akademie für ärztliche Fortbildung. Stuttgart: Hippokrates; 1944.
• Weiss RF. Herbal Medicine. Translated by A. R. Meuss. 1988.
• Weiss RF, Fintelmann V. Herbal Medicine. 2nd ed. Stuttgart/New York: Thieme; 2000.

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Connections

• Rudolf Fritz Weiss — Father of Modern German Phytotherapy
• Rudolf Fritz Weiss: Life and Career (1895–1991)
• Lehrbuch der Phytotherapie: The Textbook That Made Herbal Medicine Teachable
• Commission E, German Herbal Medicine Regulation and the Weiss Legacy
• Pharmacology: Notable Doctors
• William Withering and Foxglove
• Hawthorn
• Valerian
• Chamomile
• Gentian
• St John’s Wort
• Heart Failure