Leptospermum hoipolloi was described in June 2023 (Schmid et al. 2023). A recent paper (Chagné et al. 2023), on the basis of microsatellite data, attempted to refute the segregation of Aotearoa / New Zealand Leptospermum, preferring to recognise an endemic L. scoparium, despite obvious genetic structure suggesting otherwise. As such their view is not accepted here (see in particular comments by de Lange et al. 2023).

Schmid et al. (2023) recognised one species with three formae, L. hoipolloi f. hoipolloi (a shrub or tree up to 10 m tall), f. incanum (a shrub to small tree up to 3 m tall) and f. procumbens (a prostrate, trailing shrub). This assessment includes all three formae under the parent taxon L. hoipolloi.

Leptospermum hoipolloi is a shrub or small tree endemic to Aotearoa / New Zealand where it is found throughout Te Ika a Maui / North Island, and the north (especially north western) portion of Te Waipounamu / South Island. It is the most common or the recent segregates from L. scoparium. All three formae of Leptospermum hoipolloi have been listed "Threatened / Nationally Vulnerable" by de Lange et al. (2018), based on the perceived threat of myrtle rust disease, caused by the rust fungus Austropuccinia psidii which was first reported from Aotearoa / New Zealand in May 2017 (Schmid et al. 2023). However, these statuses were revised in 2023 to “Not Threatened” or “At Risk / Declining” as many subpopulations are considered widespread and secure over large portions of the species' range de Lange et al. (2024). Population trends and the potential threat of the rust fungus Austropuccinia psidii needs to be monitored, but for now the species is assessed as Least Concern.

This species is endemic to Aotearoa / New Zealand where it is found throughout Te Ika a Maui / North Island, and the north (especially north western) portion of Te Waipounamu / South Island. Distribution map is generalised.

Leptospermum hoipolloi is the most common or the recent segregates from L. scoparium (de Lange and Schmid 2021, de Lange et al. 2023). Herbarium specimens show that this species was once more widespread than de Lange and Schmid (2021) suggested but as those authors noted, widespread peat bog draining had eliminated the species from most of its range by the mid-1960s.

A shrub or small tree confined to oligotrophic wetlands reaching its greatest numbers in restiad bogs where it grows with Empodisma robustum and Sporadanthus ferrugineus. Leptospermum repo is also common in less acidic bogs dominated by Empodisma robustum, Machaerina and Schoenus species (de Lange and Schmid 2021, de Lange 2024). In these habitats it is often the dominant woody species, reaching its greatest abundance within the lag and rand zones of the large peat bogs. The species is also common on the damaged / partially drained margins of peat bogs.

The three formae of Leptospermum hoipolloi have been listed by de Lange et al. (2018) as follows: L. hoipolloi f. hoipolloi (as Leptospermum aff. scoparium (a) (AK284541; Auckland)), assessed as "Threatened / Nationally Vulnerable" qualified "DP [Data Poor]", "De [Designated’]"; Leptospermum hoipolloi f. incanum, (as L. scoparium var. incanum), assessed as "Threatened / Nationally Vulnerable" qualified "DP [Data Poor]", "De [Designated’]"; Leptospermum hoipolloi f. procumbens, (as Leptospermum aff. scoparium (b) (AK247250; "coastal silver prostrate")), assessed as "Threatened / Nationally Vulnerable" qualified "DP [Data Poor]", "De [Designated’]". These assessments were based on the perceived threat of myrtle rust disease, caused by the rust fungus Austropuccinia psidii which was first reported from Aotearoa / New Zealand in May 2017 (Schmid et al. 2023). 

De Lange et al. (2024) reviewed the threat status allocated these formae by de Lange et al. (2018) as follows: 

Leptospermum hoipolloi f. hoipolloi - “Not Threatened”, population in excess of 1,000,000 mature or subadult specimens, widespread and secure over large portions of its range. The impact of Austropuccinia on this formae is as yet unknown, though plants experimentally inoculated with this rust will die (Schmid et al. 2023).

Leptospermum hoipolloi f. incanum – “At Risk / Declining” qualified “DPS [Data Poor Population Size]”, “DPT [Data Poor Trend]” citing pathway C1 of Townsend et al. (2008) with a decline rate of 10-70% in next 10 years, population estimated at >100,000 mature individuals. This form is widespread within the northern part of the range of L. hoipolloi where it is mostly threatened by land clearance, the creation of avocado (Persea americana) orchards and plantation forestry (Schmid et al. 2023).

Leptospermum hoipolloi f. procumbens – “At Risk / Declining” qualified “DPT [Data Poor Trend]” “Sp [Sparse]” citing pathway A2 of Townsend et al. (2008) with a decline rate of 10–30% in next 10 years and an area of occupancy estimated at <1,000 ha. The most localised of the three formae, some populations are secure within remote, protected (reserved) land but other populations are threatened by coastal development, the creation of avocado (Persea americana) orchards and plantation forestry (Schmid et al. 2023).

In the last two formae the impact of Austropuccinia remains unknown but it is anticipated to be similar to that seen in inoculated plants of L. hoipolloi f. hoipolloi. 

Other than the potential threat of Austropuccinia the main threat to this species now is ignorance, in part caused by conflicting taxonomic opinion influenced heavily by the ‘manuka honey industry’ which has been keen to confirm the endemic status of Leptospermum scoparium – the parent species from which L. hoipolloi was segregated – suggested by Buys et al. (2019) but also desiring to accept one species to justify widespread plantings of ‘improved’ selections for the honey industry (see summary in de Lange and Schmid (2021)). Taxonomic segregation poses a problem for plantings as this necessitates more care over the location of plantings to prevent hybridization with local indigenous populations. The matter is further muddied by Maori, some of whose iwi want local the genetic integrity of local Leptospermum populations protected from the honey industries plantings and others who want widespread plantings to increase honey yields for their businesses. Pragmatic taxonomic decisions are therefore being overlooked or discredited which an unfortunate consequence to the conservation of Leptospermum of Aotearoa / New Zealand (see comments by de Lange et al. 2023).

Though easily grown from fresh seed (de Lange and Schmid 2021) the species is scarce in cultivation. All three formae are valued for the ‘manuka honey’ and so are increasingly viewed as an important resource.

Leptospermum hoipolloi next to L. scoparium is the most common and widespread of the endemic Aotearoa / New Zealand Leptospermum. Some loss is inevitable and over-arching the conservation status of all Leptospermum is the unknown impact of myrtle rust disease for which there is as yet no known effective treatment. Of the three formae, the least common and most at risk is L. hoipolloi f. procumbens, with some large populations threatened by coastal development. That forma is however secure at North Cape Scientific Reserve, Te Paki, and is also present in cultivation. Also some populations are located on remote coastal headlands and near shore islands. Leptospermum hoipolloi f. incanum is the next seriously threatened because it has a narrow, northerly range, growing in places that are used for plantation forestry, and increasingly avocado orchards (Schmid et al. 2023). Some populations are also at risk from coastal development. For this forma advocacy is needed. Luckily it is popular in cultivation. Leptospermum hoipolloi f. hoipolloi is the least at risk because it is so widespread, abundant, and present in numerous protected / secure locations on the two main islands of Aotearoa / New Zealand. All three formae are valued for the ‘manuka honey’ and so are increasingly viewed as an important resource. Further L. hoipolloi f. hoipolloi is widely planted for the honey industry.

The only other risk to the species is spurious taxonomic thinking,  which encourages the idea that Aotearoa / New Zealand Leptospermum is represented by a single genetically and morphologically variable species L. scoparium Chagné et al. (2023). This idea puts at risk L. hoipolloi because it allows for the widespread planting of ‘selections’ of Leptospermum of unknown provenance and genetic integrity so putting other indigenous Leptospermum populations at risk through introgression this is a serious ongoing risk being encouraged by the honey industry.